that sounds like the problem, we have only single springs in the rally car with a 1.5mm spacer.
they were duals but i reckoned the seat pressure would be too hi, so i took the inner out and just ran the single outers.
the seat pressures i run are about 90psi, standard is 70-75 psi i think.
(never had a problem with valve bounce, and if you do run too higher pressures you can loose HP.)
but the open pressures can get as hi as 300psi.
i'd be trying to find out what springs you have and what they should be running.
our springs were made by preformance springs, i think they're called CB4's.
they recommended installing them (both inner and outer) with a 3mm spacer.
glad i didn't.