Interesting,
could not replicate this with:
QLab 2.39
TouchOSC MIDI Bridge
TouchOSC 1.9.1
iPad 3rd Gen
5x Push Button, with OSC set to auto, MIDI set to "Value", "Note", Channel 1, Notes C-2 to E-2, Velocity 0 and 127, Local Feedback off is unchecked, Y position velocity also unchecked...
The only thing I am thinking is, if you are using QLab 3, maybe there is some sort of OSC signal that is (also) captured, that might be triggering? or maybe, another workspace is open behind, that way I have often double executed triggered script cues? Finally, check out / use MIDI Monitor, a free tool, to see what signals are actually coming in.
PS, on my QLab Config side, the lines look like: Command "Note On" Byte 1 "0" (to "4") Byte 2 "127".
Hope that helps.