Why the ._ files in game menus?

Anyone know why when you sometimes load games into the rg (I use ArkOS) you sometimes get a game file name that starts with "._" You also get the regular game name without a "._" You can't load the game by selecting the "._" one so I just go into the options and delete all the "._" named ones. It want to try and figure out what causes that so I can avoid some work. Thanks!