Only in rare cases with very special hardware on the chain.
Dell sells "PERC" RAID controllers and external RAIDs (powervaults) that are "clusterable." We have one at work. Each of two machines hava a Dell PERC RAID controller connected to an external RAID that has 2 SCSI ports (one for each machine). Both machines can access the RAID simultaneously.
But the cards and RAID are set up for that. I never heard of any other setup that allowed two SCSI controllers to control a single set of devices.