The entries "Tortuga dock", "Game of Thrones", and "Goodbye Shore!" not only appear to be quick chops that are suspiciously similar but also look like they are violating the copyright rule with the images used for the backgrounds.

To me this looks like someone trying to use multiple accounts to get enough entries to vote for themselves.

Should these posts be deleted like the ones in Ratus Plasticus?

I think we have to abide by the presumption of innocence until proven guilty maxim,after all this is an anonymous comp and we don't know who the members are until the contest is over,so they may be legitimate entries done by honest members,at the end of the comp we will have a better idea ¿no?

Alright. I guess that is true. We'll just have to see.

I think Vokaris finds them and kick them out

Yup. And everyone felt like idiots for having made them feel unwelcome afterwards.
Err on the side of kindness.

For anyone concerned about copyright infringements. It is fair use. It is fair use in the exact way fair use is intended to be used. PSC is not a 'publisher'. If a person takes a work largely dependent on that original work and decides to publish it and/or profit from it by branding, then they are liable to the original creator.
In any case, not the concern of PSC.