I do not quite get the situation. Are two Trisquel systems installed on your
computer? If so, you did not need to install Trisquel Mini alongside
Trisquel. You could just have installed the "trisquel-mini" package (and
"trisquel-mini-recommended" for lighter applications) and choose it at the
graphical connection screen (where you click on your user name). Even going
through a fresh install, why haven't you installed Trisquel Mini on top of
Trisquel (after a backup of your data, of course)?
2 GB of RAM is enough for Trisquel with GNOME Shell. My wife has just that on
her laptop. And even if it was not enough, the system would only be
unbearably slow. It would not have display issues. When you write that you
checked the RAM, was it with memtest86+? Were there errors (the screen
turning red)? If so, it is an hardware problem that no software would solve:
you need to change your RAM.
Anyway, please show us the output of the following command, to execute in a
terminal (your password will be asked):
$ sudo parted -l