Why does SB mark these two files with Action=Skip?

I am running in general SyncBackSE v6.3.13.0 on 64bit Win7 successfully.

However for one particular profile within a group of profiles I am getting curios warnings:

Assume I have two equal directory trees on my notebook and my desktop computer. When I run a certain profile then SB pops up showing always exactly the following two files (WORDS.IDX and WORDS.DAT) and marking them with Action=Skip. I never assigned such an action.
The files are currently not locked by a running prgm. They have the size=0 bytes (if this matters).

I have attached two snapshots. One showing that the twoi files in focus are selected just as other files in the same directory (which are processed correctly).

The second shows the profile description as SB shows it.

So how do I force SB to sync these two files in the same way as the remaining other files from the same directory?

Peter