Is the short form "This is the lamp, and this the telephone." correct too?

Wouldn't it make more sense as: (In a shop. Some products have been shown to you. Seller asks: Which items do you take?) "This lamp and this telephone"

There are certainly some weird looking lamps and telephones existing, but having to point to them and specify which is which sounds rather weird?

In English it is not required to repeat "is" in this type of sentence. It sounds like a Dick and Jane primary reader. It is understood in English.