It's going to be a problem while you use the same testtags.txt template since the variable names are all the same, and the last testtags.php include() will overwrite all the prior ones.
One approach is to add a smaller testtags.txt template to the other system, delete all the variables you don't want, and rename the ones you do want (if they interfere with existing variable names) -- then the new-named variables would be available without interference.