1997 M900 forks advice - please

Hello all,
I stripped the forks off the bike to change the seals, one of which had completely given up the ghost. The forks are Marzocchi's.
everything went perfectly fine until I noticed after rebuilding them, when pushing down on the RH fork the rebound appeared to be working ok (slower to come back up with the adjuster knob screwed down) however, it was nothing like this on the LH fork, seems more like a pogo stick!
I read somewhere each fork works differently on these bikes but don't know if that's true??
The oil I used was Castrol 10W fork oil, I put exactly the same amount in both.
Unfortunately I didn't check what it was like before they got stripped.
Thanks in advance,
G.