Is it possible to 'fix' old discs?

[Pushpaka]

Hi my copy of Kartia and one of
my Heart of Darkness no longer
works. That's okay as I have
the originals and can burn off
them. What happens is that
my PSX treats them as if it
wasn't modded.

Thing I'm wondering is, is it
possible to restore those
'old' discs? Those two discs
have no damage whatsoever
and I've copies far older than
those two that work perfectly.

A friend said that its some kind
of anti-copying thing involving
track timing or something. If
that's the case can I fix it or
am I sitting on a bunch of time
bombs. PSX games are so rare
now