The regular 515 is what Rathbone smoked. John doubled the amount of rum upon several requests, so he made it permanent. That is what 515 Double Shot is.
LOL, turns out I wasn't completely dreaming, you are correct, of course, but there is a little more nuance I just didn't remember.
Gave a shout out to John because I knew I had that right/but not right, haha.
Wilke No. 515 now is "back" to the original, in a sense. So if you are like me and would have ordered No. 515 in the past couple of years, it was not the same as the original blend, rum had been added a little bit (not just special orders) over time over a few years to accommodate demand preferences for more rum, but was still called No. 515. So according to John, the No. 515 I ordered in 2021, for example, would have had added rum vs. the original (didn't request it, it was just there). Recently folks were asking for a little less rum, so easier to carry the original as it was traditionally made and the more recent version now the "double shot". Clear as mud!
Since what I have jarred from a couple years ago is really the 2X, just ordered the regular and happy to now have both. Probably a little geeky, but I found the history interesting. Sorry for the diversion.