Regarding the multiple key press issue (which might be separate from a general touch screen issue as the OP might be having...)
There are a few places to tweak the keyboard response:
Options are at either the first or second locations below...
#1 - My Dell | Checkup | System Tools | Keyboard Properties .. or ... alternately from: Control Panel (use icon choices to see all items) | Keyboard | Keyboard Properties
There are 'Character repeat' sliders to tweak. However in my attempts, I saw no change in any use of the Onscreen keyboards (could be user error on my part)
#2 - Settings | Change PC Settings | Ease of Access | Keyboard
Choose to turn on filter keys (ignore brief or repeated key strokes). I did this and there was a significant improvement/reduction in the repetitive key responses for me YMMV
Additionally or alternatively accessing the keyboard settings thru the Control Panel | Ease of Access Center | Make the keyboard easier to use (adjust settings for the keyboard) | Make it easier to type | Turn on filter keys
There is an option to 'set up filter keys', which allows more precise tweaking. I did not do anything here as the first option to simply turn on the filter keys was enough in my case.
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Edit to add
As per my post further down, there is a s/w bug associated with the turning on of the 'filter keys'...which disables the 'physical' Windows button on the DV8P. So at the current time, I do NOT recommend enabling the 'filter keys' to alleviate the repeated keystroke issue. Sorry for any inconveniences this might have caused anyone. Hopefully Dell will resolve this conflict at some point.