I'm not sure I understand. You have the arp and sequencer both off, you hit the same key repeatedly and get different notes?
The only ways I can see something like this happening: (1) your voices are out of calibration, causing each voice to sound like it's playing a different note (do a voice calibration from the menu). (2) you have something connected via midi and it's sending arpeggiated or sequenced notes to the synth in response to you striking the keys. What do you have connected to your Take 5?
Lastly, this IS a Take 5 you're talking about, right? Some paraphonic synths let you tune each voice individually and run in a round robin fashion in paraphonic mode. Moog Matriarch is one such synth, and perhaps the Sequential Pro 3 does too (I don't have one so I don't know).
Edit: I just thought of another cause: mapping Voice Spread or Random to pitch in the mod matrix could lead to this effect as well. Does this happen on all patches or just one? Also if you have Vintage turned up, it can cause the voices to go out of tune relative to each other.