Are you perfectly sure that you did not mismatch two files? There was an issue with 5.18 but should not be in 5.2.
If you can reproduce with 5.2 then please create a simple testcase with a few rows of data. Create a screenshot from SQLyog DATA tab (or any other client where it displays correctly). Attach this screenshot with the corresponding dump here (or create a ticket if you want).
BTW: I think I remember that you are Czech? You have an option to use latin2 as well, I think? Is that the same issue?