Using the same template doesn’t achieve anything useful - in fact, if anything it can complicate matters.
Your approach still creates two different devices with different Auth tokens (which is necessary for proper operation) and Blynk doesn’t provide an out of the box method for device to device communication.
The HTTP(S) API method of device to device communication is the easiest to implement. This has a limit of 500,000 update calls per day, but that will be fine for your needs.
This shows you how it can be done…
Personally though I use Node-Red for my Home Automation integration with Blynk.
There’s a few snippets of info about my weather station scattered throughout this topic…
although I’ve since moved away from the BME280 sensor to a weatherproof variant of the SHT30 temperature & humidity sensor and a separate pressure sensor (which can be housed in the indoor module if you wish).
@John93 having devices share the same Auth token isn’t a great idea, it leads to confusing info about on/offline status and messes with the way that Blynk handles everything internally.
I’d guess that Blynk will put more effort into trying to detect Auth token sharing too, as this undermines the device limits set by the various billing subscription tiers. So while it might be a clunky yet confusing workaround at present, it could simply be blocked in future causing a project to stop working altogether.
Pete.