If you're using model first (EDMX) then you'll need to ensure both tables are in the same model file otherwise it'll treat the connections as separate. The connection string for an EDMX includes information about the models and not just a raw DB connection
string. Notice in the connection string that it is referencing the mapping files that are used by the model file. It isn't just a "clean" connection string.
Note that EDMX support in EF is deprecated. EF7+ doesn't support it. You probably don't want to go that route. It creates way more code than you need, is pretty heavy handled, creates connection strings that look like what you posted and overall doesn't
fit into a traditional development approach. You can use database first to reverse engineer a database but I wouldn't use anything other than the POCOs and DbContext from that point on. Without the EDMX you are back to the connection string that you commented
out. Furthermore you can separate your context into different types (a DDD thing) and use the same connection string for all of them.
Michael Taylor
http://www.michaeltaylorp3.net