you need MULTIPLE_TEMPSTRINGS or UNLIMITED_TEMPSTRINGS or so in the engine to guarentee that you the previous result is not changed by the second call.
Cos it returns from a static internal buffer.
or you can use frik_file's strzone function to dupe it before calling it the second time, but don't forget to unzone too.
in a regular engine:
centerprint2(self, ftos(5), ftos(8))
will print:
88
or so.