where can I find my "polanie1" I have in the library only "Polanie 2"

Go to KnightShift in your games library on the GOG website via your browser and there under 'Extras' on the right hand side of the screen you will find the Polanie 1 download.

Is it still there? I've just bought KnightShift/Polanie 2 and I cannot find it!

I've just checked in my library and it is listed on the right hand side under 'Extras'. However, I can't now remember if it was only available when the game was first released here as bonus, I have a vague memory that it may have been especially as it's not mentioned anywhere on the store page.

I think it was part of a release promo. The offer is no longer on the store page.

... I meant to add you to the reply also.

Does it still contain Polanie 1 as a bonus? Since I already own KnightShift on Steam, I don't want to duplicate it if part one isn't part of the package.

As it's not listed as being included on the store page I'd say no. It was only offered for a short time as a free bonus item when the game was first released here.