". . . I don't at this time know who the buyer is or what agent/company represented them . . ."
You can always ask the Listing Agent point-blank (in a non oblique manner) if the Offer came from among his own Buyers or his Agency . . . . or if it was through another Agency (Co-Broker).
If s/he says "that's confidential" or simply refuses to answer, then you pretty much know what's happening; and can start fleshing it out.
This is one aspect of brokering where the interests of the Listing Agent diverge from the best interests of his/her Client Seller . . . . because there's more commission money to be made with a modest or low Offer when it's all kept "in-house" than there is to be made with a Full-Price Offer. The Seller loses; and would have a basis for suing for a violation of the fiduciary (if they knew about it).
I had one Seller's Attorney write me, as the Listing Broker, suggesting that I had presented a Low Offer to the Seller because I would make more money than if I shared the Commission with another Agency presenting a more desirable full price Offer.
That challenge got my attention and I had to respond that there was no other offer in the offing, and that his (and my) Client's over-priced property was a real dog anyway, and probably wouldn't ever be the recipient of a better offer offer, regardless of the source; but he's free to reject the Offer.
Not a peep followed; and the Seller accepted the Offer, we Closed, and he moved out-of-State. Thereafter, I kept even better notes, and always made doubly sure I wasn't restricting anyone's opportunity to fully present any of my Listings.
But I remember it well.
Good luck to you; and congratulations on seeing the potential conflict.