For the SmartThings authorization process, when you proceed through the authorization process a second time, access to the second location effectively gets added to the existing authorization and SmartThings returns a token which has access to both locations.
With Hubitat, when you proceed through the authorization a second time and select a different location, Hubitat returns a token which is valid for a single hub at a time.
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There’s a few different approaches you can take for this, but the most common solution is the community developed HubConnect:
For hubs that are on the same network, the new Hubitat Hub Mesh could be used. Usually hubs at two different physical locations are not on the same network so HubConnect would be the preferred alternative, but in theory it is possible with advanced networking.