Since Mona's source is available on Github you can easily modify the code to fit your needs.
The code that responsible to save the files can be found (currently) in line 2477 inside the class MnLog.
try:
if os.path.exists(logfile):
try:
os.delete(logfile+".old")
except:
pass
try:
os.rename(logfile,logfile+".old")
except:
try:
os.rename(logfile,logfile+".old2")
except:
pass
except:
pass
You can download the file and modify the code as you wish. For example the following modification will change the files from compare.txt.old and compare.txt.old2 to compare1.txt and compare2.txt accordingly.
if os.path.exists(logfile):
try:
os.delete(logfile[:-4] + "1.txt")
pass
try:
os.rename(logfile,logfile[:-4] + "1.txt")
except:
try:
os.rename(logfile,logfile[:-4] + "2.txt")
except:
pass
except:
pass
I used [:-4] to remove the last four chars from the filename (from 'compare.txt' to 'compare') and appended 1.txt and 2.txt instead of .old and .old2.
I didn't check whether the modified code actually works, but it supposed to - and if not, the concept is what important here.