They might, and they might not. Every agency is different, and it really depends on their relationship and how much one agent knows about what the other is looking for—and of course, whether they're willing to make the effort to pass things along.
Sometimes a more veteran agent seems to be automatically passing queries on to a new agent who's building his list (judging by my experience and the comments on Query Tracker), so it isn't always as meaningful as you might think to have your query passed along.
Unless the agency policy states that a
no from one is a
no from all, you can query another agent at the same agency if the first agent rejects you.
I hope that covered all the reasons you might have been asking that question.