OVP (Again)

[JCE]

With all the recent discussion on OVP problems, I decided to check mine to see if it had ever been replaced - nothing in any of the records to indicate it, but I learned to distrust the previous owner's tech. My relay is a single 10A fuse, red top, ink stamped on 1 side 7477-2387, and the other side has the part number 201 540 08 45 5kwk4010. The fuse is still good, but I presume the 2387 number indicates that the OVP is the one that came with the car. When it is replaced, should it be replaced with the same part, or the larger twin fuse OVP (or is this even possible).

Also, in front of the OVP socket there is a rectangular opening about 2X the size of the OVP socket, but it is empty - no socket, just a frame opening. What was this used for?

Thanks for any info!