Try appending or linking the newer versions of the rig into the scene instead of copying and pasting. Copying and pasting may cause naming conflicts on certain nodes, or duplication of unwanted elements.
Under the File menu at the top of the screen, you'll find both the Append and the Link option. They are similar in that they both allow you to take the content of an external source file and make that content appear in your current scene. The main difference is that with an append, the contents of what are transferred are physically copied into your scene and become new, independent versions of those contents, whereas with linking, only a reference to the original content is made present, and as such, it cannot be edited outside of the original source file.
I recommend appending for now because linking is a bit complicated in some ways, and often requires extra steps, including the creating of a proxy rig afterwards. By appending, you don't have to deal with that.
If you do decide to append, though, before you do, consider putting the rig you want copied into a new collection in your current scene first, and give the collection a unique name that you can easily identify. Make sure ONLY the rig itself and its deform mesh is in this new collection, and no lights or cameras or any other extras. This way, when you do the append, and are asked for the content to be appended, you can simply choose this collection from the list of available contents, and in this way, easily ensure that you get copies of only what you want added to the scene.
One final thing. Save your current scene before beginning the append, but save it as a new version of the current file separately also, and append from the new version of the file only, not your current one. Blender doesn't seem to like it when you append from the same file that is open at the moment.