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There are a number of variables that can lead to a requirement for adjusting development times in order to compensate for differences in contrast between formats. Differences in the accuracy of shutter speeds, differences in lens coatings, differences in enlarger lenses, differences in developer flow patterns in developing tanks, etc.

In addition, sometimes the difference in rendering between the two camera systems can result in a difference in appearance that looks like a difference in contrast, but isn't.

Most likely you need to do some experimenting. If you prefer the contrast you are getting from the OM-2, you need to do some test exposures with a view of adjusting your exposure and development regimes with the Rolleiflex-T to try to match it.

You may, for example, find you need to meter for the Rollieflex using an EI that differs from the EI you use for the OM-2. You may also need to develop the 120 film for different times than the ones you use for 35mm.

Good luck.