Does a second minecraft account cost anything?

If I want to play with a second account, will it also cost 20 euro?

Yes of course

why do you need one?

Yes. You have to buy Minecraft 2 times.

Yes…

If i don't stay on my plot no new mobs will spawn. According to server rules, it is allowed

A second account also costs something! Because otherwise everyone could have thousands of other accounts and sell for less money and the makers of minecraft would be broke at some point ^^

Well that makes sense.

Naturally.