show grants for someuser not working for root
I'm only guessing here, but could it be that you have defined different host values for someuser on server1 and server2?

When you execute SHOW GRANTS FOR someuser; it really executes SHOW GRANTS FOR someuser@'%'; - that is, if you don't specify the host part, the it will default to using the wildcard (%) for the host part. 

So if you have someuser@'%' on server1 and e.g. someuser@'localhost' on server2, then you will get the result you have observed.

You can see the host part of the users by executing SELECT user, host FROM mysql.user;

And then you can view the grants for the different users by executing SHOW GRANTS FOR someuser@'localhost'; or similar for users with other host values in their mysql.user rows. Note that each row in the table is a different user - it doesn't matter that some of them might have the same user names as long as they have different host values.