yes, StorageTek allows you to do this with their acsls software. I have seen this done in a powderhorn silo but I do not know the configuration procedures.
Here are a couple of Tek-Tips threads on sharing
ACSLS - Define Volume Owner
http://www.tek-tips.com/viewthread.cfm?qid=408943
Share L180 between 2 different software?
http://www.tek-tips.com/viewthread.cfm?qid=388250
Here is a thread in a discussion on Auburn VERITAS newsgroup
One ACS robot, two NBU masters
http://mailman.eng.auburn.edu/pipermail/veritas-bu/2005-November/031692.htmlBS