Yes it seems like the second Player which is connecting is always a local 2nd player. So it does not matter if the 2nd Account is a Member, or any other player it always spawns at the same local 2nd player. It seems like its just changing the Name of the ”copy”. There is not a Real Connection between the Account and the Minecraft Server. The Account gives just the Player Name no linking to Saved Data.
And also you don’t get the Same permission. If the owner of the realm is the second Account he should probably get also visitor Status and Nobody could even Change that