Dunno. What exposure are you using? How are you metering? Which exact filter do you use, i.e. what wavelength? (Mine is a generic uncoated-glass Chinese R72 clone, i.e. 720nm cutoff)
If it's always overexposed, did you, um, try exposing less?
The IR820 is definitely better (more Woods Effect) than the Rollei in side-by-side comparisons, but I've seen decent results from the Rollei on flickr too. And certainly I'm hoping the Rollei isn't toooo bad, since I bought 200' of it in 70mm to use once my little stash of 120 IR820 runs out (4 rolls left). Happily I have about 370 sheets of 4x5 too