RTR ( P ) and RTR ( C ) are not issued lifetime validity ( to the best of my knowledge , i could be wrong )
Only RTR (A) is given lifetime validity . To get an RTR ( A ) you have to pass both part 1 and part 2 .
If you read item number 6 in link below you can understand what I mean by the above two statements
http://www.wpc.dot.gov.in/DocFiles/copcircular1.jpg
However if you look at the result page you can see a form called 'Undertaking' . I think using this form ( especially the second option ) you might get an RT license with lifetime validity .
To 100% clear your doubts i would suggest you call up the WPC with your queries .
The Telephone numbers are given on the result page