direct record only in stereo?

No matter what I configure in the sample record window, the direct record feature delivers only a stereo sample, resulting in my analog monosynths being recorded only on one channel. For every new recording I have to leave the main mode, go to the trim section, convert to mono, delete the old sample and replace it in the program. Is this a bug or do I get something wrong?

MFB Dominion 1 and tons of vintage synths. No stereo outputs on most of them. I could use a mixer inbetween but l+r mono recorded into the MPC as stereo = double memory usage for the same data on each channel.

any help on this? it's not featured as a bug yet... do i get something wrong?

Used a Y audio cable? Might have to normalize after sampling for its signal is being split.