You can not have multiple GI running on same server.
Please review the following note:
11gR2 Clusterware and Grid Home - What You Need to Know (Doc ID 1053147.1)
11gR2 Clusterware Key Facts
"Only one set of clusterware daemons can be running per node."
Also refer the following RAC faq note and you may get answer for most of question
RAC: Frequently Asked Questions (Doc ID 220970.1)