I just downloaded the battlefield 5 trial on origin and I got 2 copies on gog galaxy. Also, I had the titanfall 2 trial, then I bought the game but I still have the trial version on galaxy at least.

That's quite normal and it works like that in most launchers (Origin, Steam, Uplay...)

You can always hide any demos, betas, or free to play games that you don't want to see (right click the game and select "hide this game")

I wish there was a way to "delete" games from 2.0. I have Wallpaper Engine on Steam, but I really don't need it to be in 2.0. Generally speaking, I'd like my hide list to be things like separate DLC or games I just don't much care for. I have no need for free demos/trials and programs.

Oh I do that, but then you get the ugly "there is 1 hidden game, show hidden only" thing at the bottom. Obviously not a deal breaker or anything like that but yeah, I'd rather they didn't show that or maybe not count the demo/beta as a duplicate.

Yeah, it's annoying. Unfortunately, it seems the problem lies with the other launchers/platforms. We'll see if GOG Galaxy will be ever be able to deal with that.

There's a workaround for such demo/betas/free games from Steam, though:

https://store.steampowered.com/account/licenses

That site lists everything you own (ever) on Steam: you can then delete the demo/betas/free games. Be careful to not delete something you might want to keep though!

It doesn't deal with all of them, but for the most, yes. (only on Steam!!)