[polli]

I have used Calibre for a long while But mainly to add epub books..
I have now got a few of the same books in Kindles.
How do I add them to Calibre when a message comes up saying that title is already there?
One I managed to add last week shows as jpeg I added. But greyed out. Don't understand that. Why is it not blue as kindle?
When epub is dark black.