Radar tag "split"

[caucatc]

This is what I experienced :after an aircraft airborn ,I found a secondary surveilance radar signal flied together with that aircraft ,everything is same except a different squawk ,I let the pilot check the transponder again and again ,but still not fixed ,it just like another transponder has been attached to that aircraft and the pilot can't find anything from TCAS either.
What should I do ? Should I terminate the radar control and begin procedure control ?:ugh:

[055166k]

I have seen this with certain types of transponder. Make a note of any similar occurrence to see if it is the same type of aircraft.
You need to make a record so that all the relevant details can be compared.
It could be a compatability problem between air and ground equipment, and keep the radar recordings to help with any investigation.
If it happens again.....ask the pilot to change transponders if he has another....it may help to isolate any fault.