I finally figured this out!
It is an HTC specific issue!
HTC has an option called HTC gestures.
It allows 3 finger output gestures.
This is interfering with the exporter.
If you turn this off, you don't get the accumulation issue.
You do however get the negative touch issue, even with this turned off but you have to rap the screen with 2 fingers alternatively very fast so this is a lot less likely to replicate by accident and also doesn't seem to break games like too many touches.
Now that I've sussed exactly what's causing it I'm not sure you can fix it but you can at least you can document it.
I can also continue development knowing I'm not going mad lol.
I did find this nugget during my research, not sure if it helps.......
"The three finger swipe is registered as a keypress, namely key 250 (by default allocated to the action HTC_SHARE). See system/usr/keylayout/cy8c-touchkey.kl for references. "