Yes, this happens. There are already about a dozen threads about it.
The issue will be reported as either:
“My Hub is missing from the IDE” (it’s not, it’s in the second location the system magically created)
“I have two duplicate locations now” (yes, you do, the system magically created the second. If it’s empty, you’ll eventually be able to delete it.)
Or your situation: “I have two locations now. My hub and most of my old devices are on one, and my Samsung appliances and TVS are on the other.” (Yes, that happens. The official Knowledgebase article tells you that you can move the hub and its devices into the location that has the Samsung devices, but not the other way around. Then once you have an empty location, you can delete that one.)
Anyway…
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the answer to where the second location came from is that Samsung magically creates it if you had an original SmartThings account and now you have a Samsung account. As I said, many existing threads in the forum about this issue.
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Televisions and appliances now need to be managed with the new app. As you note, they won’t work with classic. (Many existing threads on that as well, btw.)
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it’s fine to use both apps at the same time, which many people have to right now. See the FAQ:
- to be honest, I’m not sure if you can use your televisions with Webcore or not, given the current state of things. Webcore has their own forum now, and you’ll get your fastest and best answer by asking there.
https://community.smartthings.com/t/introducing-the-new-webcore-community-forum/96259
If what you want to do is move your hub with all of its devices over to the location that has the televisions ( it won’t work right if you do it the other way around), here’s the official knowledgebase article that tells you how to do that:
https://support.smartthings.com/hc/en-us/articles/115002084986-Locations-in-the-SmartThings-app
So that will get everything together again, but what I don’t know is if that means webcore will be able to access your televisions. I don’t think so, but I’m just not sure. Ask in the webcore forum and they should know.
Research Results
BTW, Here are just a few of the existing threads on the duplicate location issue, they should give you more details on points 1-3 above if you want them, although at this point they probably are moot as long as you read the official knowledgebase article on locations.
Next time, research a little more before posting your question so you can focus on the new stuff and save us all some time. 
All of the following threads are talking about the same issue. 
Duplicate Locations now in ST Web Portal
Migration to Samsung Account: duplicate location?
IDE webpage suddenly shows 2 home locations - wont let me delete - I only have 1 hub
Migrated to Samsung Account - all devices are "unknown" in new app
Extra / Phantom Home Location created by new SmartThings app, Why?
And the official ST knowledgebase article:
https://support.smartthings.com/hc/en-us/articles/115001554526-Samsung-Account-Update-FAQ
Point 4 may already be answered in the Webcore forum, you’ll have to check there.
(@jkp May want to create a FAQ about it, since the question gets asked about twice a week and @jkp typically provides the answer. )