If you do this, you need to have a very explicit policy for contributors to say they are contributing under both licenses, though this is something you need to have anyway if you are licensing under Apache 2.0 (a contributor could theoretically claim retroactively that their contributions were all MIT licensed and that they never gave you or any of your users a patent grant). (Most Rust projects do this.)

For other patent-shield licenses such a combination also removes most of the protections of the patent shield (a patent troll user can use the software under MIT and then sue for patent infrigement). However, the Apache 2.0 patent shield is comparatively weak (when compared to GPLv3 and MPLv2) because it only revokes the patent license rather than the entire license and so it actually acts like a permissive license even after you initiate patent litigation. This makes the above problem even worse -- if you don't actually have any patents in the software then a patent troll can contribute code under MIT then sue all of your users without losing access to the software even under just Apache 2.0 (I don't know if this has ever happened but it seems like a possibility).

IMHO, most people should really should just use MPLv2 if they want GPLv2 compatibility and patent grants. MPLv2 even includes a "you accept that your contributions to this project are under MPLv2" clause, avoiding the first problem entirely. It would be nice if there were an Apache 3.0 that had a stronger patent shield but still remained a permissive license (MPLv2 is a weak file-based copyleft), but I'm more of a copyleft guy so whatever.