I can not answer that question. I do not know how to get it to override its internal data base if it can at all. I would suggest you call the iPronto help desk, but based upon the feedback I see here they are about as useful as ants at a picnic.
I only use a single IR format which is actually a very common one and always paste the code in. For some reason it always accepts it.
Looking at your pattern, it is one of the common ones. I call it the NEC with shorthand repeat format. It is used by pioneer and many others because there is a standard chip which receives and decodes it. try the following. Change it to one of the following.
Pattern a is a one time pattern with no shorthand repeat. You can use that for all cases where repeat is not desired such as poweroff.
Pattern (b) Is a repeat pattern which will work for one time or repeat because the full pattern will be repeated.
Pattern (c) has both the one time and repeat sections filled in.
Maybe the ipronto will not convert that to its internal format.
Let me know how you make out. If it keeps the learned pattern, but it is still unreliable, then the pattern is probably bad, or your IR signal is blocked, noisy etc.
Curious - Are you using a Plasma display? Plasma displays give off a lot of IR background noise which is often picked up along with the proper IR data and tends to drop the recognition rate (Kills signal to noise)
