Hello,
An interesting question. I don't know if it was common.
I believed that this could be explained by the possibility that there were two (2) separate actions on dates, which were not too far apart time-wise, that led to the award of the EK2 and the EK1. The award requests were then processed, and awards could have been made on the same day for previous actions on separate dates.
Of course, the Regimental History may help: https://books.google.com/books?id=5fzFAAAAMAAJ&printsec=frontcover&source=gbs_ViewAPI#v=onepage&q&f=false
Or of course, if one had the award documents in hand, they might list the date of action and the date of award.
But, I suppose that if an action on one (1) date was of sufficient merit to award an EK1, and the Officer had not already been awarded the EK2 (usually a pre-requisite for the awarding of the EK1), then both awards could have been processed.
Best regards,