In the second one the clicks were more audible, and yes, that's exactly what voice stealing when playing in that style sounds like. The envelopes reset from a non-zero value, which causes an audible and varyingly subtle transient, or click.
In short, the OB-6 is a synth, not a piano, and you can't expect piano-style playing to work well with it. You can mitigate some of that with shorter release (for playing like that with many notes following each other polyphonically, you might need a very short release indeed) and playing, as I mentioned before, with fewer notes if you want some of the previously played notes to ring out.
This is a classic issue with low-voice count polys and people used to near-infinite voice counts. You'll adjust your playing style if you pay attention to it and learn how to use the synth engine to tune a sound for what you want to play on it.