"Highest & best" - any way to verify a multiple offer situation?

[Karen Miller]

Hello BP Experts! I'm a newbie who has been out looking, running numbers, and finally made an offer. Then I'm notified there is another offer and they are asking for "highest & best." How do I know there is really another offer and it's not a technique used to drive up an offer price? Is this what I should expect (in FL in the <$100K market)? Thanks in advance for an advice/education :)