The Vim plugin is very nice, and its use isn't restricted to machines where Kamailio is installed, as the config file can be edited via network (e.g.: using netrw plugin).
Currently the most common approach to retrieve a Vim plugin is to clone its GitHub repo and use some plugin manager, such as [pathogen](https://github.com/tpope/vim-pathogen).
But it clearly doesn't make sense to retrieve the complete Kamailio repo only to use the vim plugin; this probably caused the creation of [duplicates](https://github.com/eloycoto/vim-ser). I actually find that duplicate first, and then noticed on its README that there is an official (and newer) version here.
Do you find acceptable to move it to a [git submodule](https://git-scm.com/book/en/v2/Git-Tools-Submodules)?