Dear ArghyaC,
no this would not work.
The variables coordinate_x, coordinate_y and coordinate_z should not be changed. The script passes the values stored in these variables to FLUKA.
Also the second calling the regionsource subroutine will only overwrite the first one.
You should use a random number and an if ... else structure to select one of the regions, similarly to my previous post: Multiple complex source in Fluka - #2 by horvathd
Cheers,
David