TeraByte Unlimited

Hi,
in addition to an existing Win10 I want to setup another Win10 on the same disk. I setup two boot menu items for each system.

I set all the partitions of the existing Win10 to "hide" and "MS:Hidden", but all of them are visible in partition manager of Win10 Setup.
Why are the unwanted partitions still visible?

Using GPT

They will be visible but you can't mount them. It doesn't remove it from the partition table so that you don't have to worry about it not knowing something exists there.