To fix this issue For the users in primary userstore, you can simply use their username. (eg. userX) But, for the users in secondary userstores, you have to use domain/username to identify them. (eg. domainX/userY) When you have multiple userstores, you can have only 1 primary one, and rest should be secondary. There are no advantages or disadvantages as such.
wish helps you You can use the secondary PHY to talk to other devices supporting the secondary PHY. Why would you want to do that? Majority of devices today use the primary PHY, so by moving to a secondary PHY you avoid collisions with the existing primary PHY ecosystem and get improved communication. On the secondary PHY the bitrate is double, so it comes with all the advantages of a higher bitrate.
Difference between Primary GIC vs Secondary GIC in ARM