You can copy objects in a matrix model and paste them into the same or another matrix model.
Copy and paste objects
Procedure
Open a matrix model.
Open a graphical model.
Select one or more objects in the graphical model.
Click Copy or use the keyboard shortcut Ctrl + C.
Click the relevant position in the matrix model.
Click Paste or use the keyboard shortcut Ctrl + V.
The objects are pasted into the matrix model as occurrence copies.