Seeing the same amateur stations in contests / 2017-02-24

As I process the eqsl confirmations that come in after the Russian Worldwide PSK contest 2017 I start to notice some callsigns are showing up regularly in (digimode) contests. My highest number of confirmed contacts via eqsl which are related to contesting come from YO9AGN, S58X, S51AF, RA3GZ, HG3FMZ, EA3HKA, 9A4FS.

But the number one callsign I have confirmed via eqsl is not a contest station but the Veron club station PI4AA where I try to call in to the net almost every month.