thierryg, I tried both and I had the same result. If I changed one register, both are changed. Like you said the two cores seems to have their MSR registers linked.
But, in doubt, I change MSR registers for the two core.

Guys you're kings!!!! Thank you very much! I use your work but translated in french in the : hardware.fr forum . It's a topic about DM1 3130. I explain that it's your work and I put a link to this topic. thierryg, could you read my post on the french forum and tell me if I didn't say too many things...