I already have a previous version. Should I uninstall it?

Yes, all desktop application components (of previous version) should be removed before installation of version 6.0. To uninstall it completely here are steps to follow:

             1- Uninstall TelegramFxCopier from Control Panel

             2- Remove Folder "TelegramFxCopier" and/or "TelegramfxCopier_V6"  Located in: C:\Users\[USERNAME]\AppData\Roaming\MetaQuotes\Terminal\Common\Files