That is a wrong assumption that you would save some space by doing this.
I though the same before, and here is what I did on a system with IC5.0,ICC11, SPW, SPR, and LDV, and also lots of PDKs:
1- run a MD5 checksum on all files
2- do a diff on all files that have identical MD5
3- run an ls -l and awk script on identical file to see how much space I save.
The plan was to replace all the identical files by symbolic links to the file that has the shortest path. But I did not do it, because step 3- showed me that I would save only 1GB on a total of 14GB