Too many questions within that question. How much time passed in between the two offers? Is the $300,000 an overprice? Is $250,000 a market value?
Under 'normal' circumstances, no, it's ridiculous. I wish I could say I've never seen anything more astoundingly lame . . . except I have. LOL
PS. If it was my seller and the offer came in through another agent, of course I would submit it. If my buyer wanted to do that, I would probably cease working with that buyer.

It is the law that all offers be submitted to a seller. They don't need to respond or to accept, but you must submit.

Have to present them all but I also tell the agent prior offers were not accepted for that price.

The answer may be "it depends" while remembering that all written offers must be submitted to the seller.  "It depends" may enter the scenario "if" the seller has expressed(and there is proper documentation) that they do not want to see any offers under a certain price.      

Most buyers/sellers don't understand our obligations unless we explain the "rules"(and sometimes it requires repeatedly explaining).   Upfront conversation with our sellers regarding offer presentation needs to take place -- they are the decision maker, we guide but not decide.   

Depends on circumstances. If 300 is fair market value, I would tell buyer that a 250 would probably be rejected since seller already rejected a 300,000 offer.

If my seller denied an Offer for $300K and I got another one in on their behalf for $250K, absoultely, I would submit it. Regardless of the price, I submit all Offers.

Even if the seller said no to the $300K and said, "Don't bring me any Offers less than $325K," I'd still let them know that I received that $250K Offer.

There is so much  "depends" in this question that it might as well be a television commercial at a senior center.

Let's make the presumption that when the offer for $300,000 came in, my seller, as I was leaving her house, threw the loose paperwork over my head and screamed at me "And don't bring me any other 'lowball' offers like this again!" slamming the door hard enough that the all the neighbourhood dogs started barking in unison.

So, under those conditions ... no ... I'm not bringing her a $250,000 offer... I ain't got no death-wish.

Depends on the written instructions from the seller...

Unless I have written instruction as to which offers not to submit I would submit all offers (written or verbal).

I would.  It's not for us to determine what our seller will and will not deny unless if we have something in writing and signed by seller that he will deny any offer $300k and under.  The house may be sitting on the market for a month when the $250k offer comes. He may be motivated to sell by now. 

What's the price and what do the comps say?

Yes, required by my listing agreement to submit all offers.  However I would let the agent know that higher has been rejected just in case reconsideration of the offer is on the table.

Talk to your client and obtain their instructions. 

        I have to present all offers, etc.  But I'm not going to invest much time on it.  Email it, have the Seller acknowledge receipt, let them decide.

I'll go with Lyn Sims on this one. No use in blowing smoke to the buyer's agent!

Have to submit all offers to your seller is that the rules are 

What Nina Hollander said. -Kasey

All offers must be submitted to a seller unless a seller otherwise states: Do not send me any offers under X amount. 

We submit all offers.

Yes, because I am obligated to present all offers to my client.

Unless the seller told me to not submit any offers under "X" amount I would submit all offers. Clearly this offer would be presented in a quick text or call. 

I personally like to not have to deal with me being on the wrong side of the law, so I am presenting all the offers. I like to get a signature on everything to be able to get something back to the cooperating agent just as proof the offer was presented. Knowing the law helps everyone involved.

No, are you kidding me...

Karen Jones Lewis, MBA, Realtor Yes, we are required to present all offers to our selling clients.

It all depends on the terms as to whether seller might accept. As far as submitting, you have to present everything, it's not a choice for the agent.

It depends who you are in the transaction ?

Actions would relate to the circumstances.

All offers must be submitted to the Seller, no matter what price.  They always have the option to decline or not answer.

Everyday is a new situation, deliver all of the offers.

We are required to present any and all offers to our principals. We let them decide the next step.

If it was my seller, I would submit the offer as required by law.

Karen Jones Lewis, MBA, Realtor - Our job is to submit the offer!

It is a different time. Seller's motivation does 'fluctuate'!

And as I mentioned, unless the seller has instructed you not to present such offers, I'd alway present it.

You never know, the 300 could be VA financed wanting 15k back (I've seen it) in seller covered expenses and the 250 could be all cash.  Now if the seller said "I don't want to see anything under 350" I'd tell the 250 agent that and not to waste their time.

Isn't it your job to present all offers? 

Yes, as I'm required to present all offers.

All is negotiable but is it worthy? Ignorance, trial & error and many bites at the apple can offend some and win over others. First read it well & then act

I will set the low limit with my Seller at listing and adhere to that number contractually. No unnecessary effort for offers not meeting that threshold.

What was original asking price and do you think it was overprised? I would not send another low ball offer only if that low offer is based on recent sales. 

Submit unless I've got it in writing to not submit any offers under XXX

I will call the agent apologize and ask if the seller will consider that price range first. You can be labeled as a low ball agent.