Question why is plesk creating more subdomain folders?

[HOSTMARCEL]

so i have for example:

example.net

so inside C:\inetpub\vhosts there is example.net
I create a subdomain test.example.net
a subfolder will be created in C:\inetpub\vhosts\example.net\test.example.net
BUT! it also creates a folder on C:\inetpub\vhosts with the same folder name.
and there's nothing inside...
I'm just wondering why does it do that, and if it should not what can be causing it.

NOTE: this is just for the sub domains

regards,
Marcel