NO NO NO! libgles2-sgx-img is a library giving your device OpenGL ES 2.0 support, while libgles1-sgx-img gives your device OpenGL ES 1.0 and OpenGL ES 1.1 support. 1.0/1.1 and 2.0 are different and NOT compatible libraries, so you should be able to install both of these libraries concurrently and they should happily coexist on device. You can always try opening good old terminal and type:
It will use default package manager (not FAM), maybe this is the case (as these packages are made by Nokia and I remember that one time in the past when someone in FAM thread stated that it has problems with some Nokia-made packages like SSU updates etc.). After that try installing gltron again with FAM

Edit: if it says they are already installed and nothing to do, try "apt-get install --reinstall libgles1 libgles-sgx-img" instead)