well, truthfully, it does look bad as they usually allow you to do more than 4 if you prove you are capable, that is getting P's at least. Nothing to lose in asking your course co-ordinator however.
The only problem with doing 5 subjects is only time management, all the assignments are due at the same time. So you may find you are putting less effort into some subjects to compared others.
Also, you only need to repeat the subject if it was a core.