I had something somewhat similar when I tried to run both amd and nvidia card at the same time (and same computer) with 2 different instances.
The problem is due to multiple access to the dag files (and obviously it should be avoided).
I solved the problem by compiling a second miner where the dag file are written to another location and now both miner can run at the same time (each of them writting and reading dag files located in different directories)
I have been struggeling with Ubuntu since yesterday and i have got alot of help from a nice guy at ethereum forum.
I think i will be up and running soon hopefully.
I will clone that ssd disk for use on my other rigs. I hope that works.
what are you using to clone the ssds ? i tried clonezilla but i could not get it to recognize the disks on ubuntu 15.4
Not sure how Linux works with clones ?
I got my first Linux rig ever up running this afternoon with alot of help.
The testrig is up and running and sprnova reporting 10-12Mhs with one EVGA FTW 750Ti.