It has been reported that Microsoft has indeed launched a BOGO deal for both handsets but unfortunately the promotion is only live in Canada. It is possible that it will eventually make its way stateside, but at this time of writing on those living in Canada can take advantage of it. The deal is also pretty straightforward in terms of participating.
Basically this only applies to the Lumia 950 XL, in which if you were to purchase the handset for CAD $849, you will be eligible to receive the Lumia 950 for free. Both handsets are unlocked meaning that you can use them on pretty much any carrier. This is in fact a better deal than what carriers typically offer, in which the free handset is usually credited back to customers over a period of time.
There is a catch in that customers are only limited to 2 each, which obviously is put into place to prevent people from buying and hoarding them to resell. The offer is also limited while stocks last, and will run from the 25th of April until the 1st of May, so if you’d like to get in on this, hit up the Canadian Microsoft Store for the details.