I cant merge

git checkout pc // 'client' folder appears
git status // nothing to commit
git checkout pc2 // 'server' folder appears
git status // nothing to commit
git checkout master // empty repository
git status // nothing to commit
git merge pc // already up to date
git merge pc2 // already up to date

Why i cant merge master with pc and pc2? I expected merging in last two lines. For some reason it says that master is already up to date, but it is empty. 

Did you try pushing it to GitHub (just to test). You can then visually compare the two branches which may clarify why it won’t work.