With Discover/Engage 2013 or later, once you manually start the Discover.mbx application, there are no issues in having multiple MapInfo Pro versions installed.

Note however that we do not support the simultaneous running of multiple instances of MapInfo Pro and MapInfo Discover. This includes simultaneously running MapInfo Pro 12.5 64-bit and MapInfo Pro 12.5 32-bit/Discover 2014.  Issues will likely occur with some advanced modules (such as Drillholes, 3D and Graphmap).

With previous versions of Discover (pre-2013), you can have multiple MapInfo Pro versions installed; however Discover will only fully (correctly) install onto the last (most recently) installed version of MapInfo Pro.

For these older versions of Discover, you will need to navigate to the MapInfo Pro program directory for the version that Discover has installed to, and manually copy all EncomXXXX.XHX grid/raster handler files and the ERMapper_u.dll to the other MapInfo Pro version's program directories.

You will also need to manually start/run the Discover.mbx when opening other versions.