How to merge duplicate Apple watches in Health App Sources

I am using a first Generation Apple Watch and upgraded from an iPhone 6s to an iPhone 7.

Before setting up the iPhone 7, I followed the steps detailed in the following link to unpair my Apple Watch from the iPhone 6s, back up to iCloud and wipe the old device back to factory settings: https://support.apple.com/en-us/HT201351

I then set up the iPhone 7 from the iCloud backup. Once everything was restored, I had to pair the Apple Watch with the iPhone 7. Ever since, the health app shows the same Apple Watch twice in the Sources list. One is listed as "This Apple Watch is no longer paired to this iPhone" and appears to contain all health data prior to my upgrade. The other appears to contain all health data from the upgrade onwards and is the currently paired device.

My question is this: is it possible to merge these two devices? I mean they are one and the same device! I don't want to lose any health data - how can I get my phone to understand that these two devices are the same device?

What caused this problem in the first place? I followed apples instructions to the letter and yet here we are...

Any help or input would really be appreciated - I'm slowly going insane here trying to figure out a fix! Thanks a bunch in advance!