50g

When using my 48GX I've never had a problem, however on my 50G when I 
am trying to duplicate a number (i.e. 55, 00, 88, etc.) I seem to be 
pressing the key too fast and it only records one of the numbers.  It 
seems as if the system has a delay in it where it thinks I've 
accidentally pressed it twice and does not record the second one.  
After getting a couple of calcs wrong because I wasn't watching the 
screen I tried again on the 48 and had no problems.  It there an 
adjustment for this in the system somewhere?  I've gone through the 
manual and could not find one.

Thanks much,
Robert