Can you do it? Yes. It is supported? I do not know, and you may want to
ask the company officially for that kind of answer. In the past I was
told that it was not supported (SUSE Manager 2.x) but I have not asked
since then.

Alternatively, if you turn up logging (rhn_check -vv) and then kick off
the migration you can easily see the commands that it runs, which are just
'zypper' commands. As a result you can do multiple SP migrations/upgrades
using the commands and achieve the same end results nicely without
techniclly using that particular one-server-at-a-time feature of SUSE
Manager, and that is, in my opinion, supported, and a couple clients of
mine have done this in the past.

Good luck.

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