Different sitenames for internal use

Hello,
I’m wondering if there is a way of defining differing sitenames for internal use? I have created three multisites with slightly different names, so that’s easier to distinguish them in the admin-interface:

http://s32.postimg.org/g9ekwnkxx/multisite_names.png

But as it seems, wordpress uses these names also as sitetitles for the individual pages in public and SEO Yoast refers to these titles multiple times, so it’s not sufficient, just doing a str_replace on the wp_title() function in the template-files.
Is there a way to overwrite/replace the sitetitle-variable in general? I just want to see “example.com” on the frontend, without the language addition, I added for easier handling on the backend.

I hope my question is clear enough, otherwise don’t hesitate to ask further queries.

Thanks for your help.