>>Is there a way to create a model LEAP consisting of two LEAP areas?

This really depends on how your two existing models compare with each other. If they have exactly the same branch structure, scenarios, fuels, & effects then you could potentially do the following:

In this example, assume a country (Country X) made up of two provinces (P1 and P2) and that you have two existing one-region models for P1 and P2.

1. Save one of your provincial models with a new name (e.g. Country X) initially containing just one province (P1)

2. Add a new region to that model for the other entity (P2).

3. Open the existing model for P2 and then export all its expressions to a spreadsheet (using Analysis: Export to Excel)

4. Adjust that spreadsheet so it can be imported into the country model (e.g., change the area name and region IDs in the sheet). You should also review the scenario IDs and branch IDs to make sure they match between P1 and P2. These IDs are located in the first few columns of the sheet and are hidden by default so you will need to unhide the first few columns of the sheet.

5. Import that sheet into the new Country X model.

Note: don't expect this to be a fully automated process. You will need to carefully check the imported region model and non doubt will need to adjust some of the data and expressions!

Importing works best when importing by branch ID, but if these differ between P1 and P2 then you can also import based on the full branch names.

One other thing to watch out for is user variables. If these differ between P1 and P2 then things will get more tricky. You should ensure the country model contains the superset of user variables across P1 AND P2.

One more thought, for multi-regional models it often makes sense to create an extra non-calculating region (I usually give these the name "template"). You can specify that all other regions inherit their expressions from this template region. Its important to make it non-calculating so it does not contribute to the results shown for the model. I use the template region to contain any data or expressions that are common across all regions (for example: this might include emission factors or energy intensities). You can also always override the default template expressions in any particular region if needed. Taking this approach reduces the data you have to enter for each region, and makes it easier to maintain the model going forward.