Are there aircraft with multiple inlets for a turbojet engine?
It’s common on military fighters. For instance most single engine fighters eg F-35, JAS-39, J-18, etc. will have a pair of inlets on either side of the fuselage feeding these single engine.  Some aircraft will have auxiliary air intakes eg B-2, F-117, F-22, MiG-29/35, SU-27/30/33, etc. to provide additional air on takeoff or other high power settings or to provide protection against FOD ingestion.