I have mainly read that its more about size then age. They say you don't want to put a large glider with a small glider that could get bullied. it sounds like
they are similar age.
Also don't forget to read about scent training and introduction procedures,
that are available on different websites. gliders are territorial and some
don't want company.
My wife has introduced several gliders, usually lone gliders are very happy
to have company and a colony. Once we had a larger colony, one became the alpha
and he is now very hard to expect new additions to the colony, but we are at 6 in
the colony and that is just right for us.