Error with multiple roles assigned

Hello,
I think there is an error with the added roles.
Weird thing is happening, when a user is assigned more than one role, the capabilities decrease instead of increase.

For example, if it is a Publisher role, I assign an additional Subscriber role, this last role will subtract some Publisher capabilities from the role.

Normally the roles should add up and add capabilities to the topmost role and not the other way around.

Thank you