When you are building some app in an ecosystem not entirely managed by you, things like this are bound to happen, so there are always ways to solve this.

You use Foo1 in Project1 (= one pom.xml) and create Project2 (=second pom.xml) where you use Foo2 (but package it in such a way that Foo2 is not exported from Project2), and depending on the usecase create a thin wrapper which you can then use from Project1, as an absolute worst case.