Pasting restricted data in cells with validation

[Isito]

I have a form where I use the data validation to restrict entering some of
the data. However even though the users cannot enter some of the data they
still can copy/paste anything from the different spreadsheets. The sheet is
password protected and they cannot change the formatting however when they
paste stuff from the other spreadsheets the formatting is also overriden.

Do you know if there is a way to only allow paste special - values and also
check the data when it is posted to the cells with validation.

Many thanks