Connect 2 x DDJ T1

How do you mean - audio from one output to the input on another?  Yes, you can do that, but be aware that on the 2nd unit (receiving the audio from the 1st) you will only have 3 decks available as you must assign one of the decks as the input for the AUX.

Thanks! But is it possible to control with 2 controllers (DDJ ergo & DDJ t1) one Traktor?

(Or is there any other way to DJ with 2 DDJ controllers?)

Sure, you may need to customize the mappings tho.