OPNsense Multi WAN, 2 Interface or 1 Interface?

[schtebo]

Hi,
i have one question regarding "OPNsense Multi WAN".
I found some articles/docs and videos. They all use for this scenario 2 Interfaces with 2 different IP networks. For example:
External 1 Network = 192.168.0.0/24
--> LTE Router: 192.168.0.1
--> OPNSense: 192.168.0.200
 
External 2 Network = 192.168.1.0/24
--> DSL Router: 192.168.1.1
--> OPNSense: 192.168.1.200

But is also possible to use only 1 Interface (External)? Like that?

External Network = 192.168.0.0/24
--> LTE Router --> 192.168.0.1
--> DSL Router --> 192.168.0.2
--> OPNSense --> 192.168.0.200



Thank you + BR