Webide is not able to create multiple offline store which are configured in SMP
How many OData services you want to use in your application? Are those from same datasource like SAP?
In general, there should be one OData service per application. So you can have one offline store having multiple collections.
You got an option to select 'Odata collections' that will be cached for offline store while creating a project from 'offline' template. You can add more OData collection manually in the devapp.js file as well.
There is no purpose of creating destination connecting to SMP (except you want to use OData service exposed via Integration Gateway (on-premise) with SAP Web IDE Cloud )
What limitation do you see when you select more than one collections for offline store
Regards,
JK