I want 2 ethernet interface of one router to connect in one switch in a local network. What method is correct?
1.
ip address/
add address=10.10.10.1/18 interface=ether1
add address=192.168.1.1/24 interface=ether2

Is it possible to connect so...?
2.
ip address/
add address=10.10.10.1/18 interface=ether1
add address=10.10.11.1/24 interface=ether2

I dislike both methods. Strange behaves ip arp

There is such at the first and second method:

Before connecting of ether2:
/ip arp> print
# ADDRESS MAC-ADDRESS INTERFACE
0 D 10.10.10.1 xx:xx:xx:xx:27:5E ether1
1 D 172.168.0.2 xx:xx:xx:xx:3B:9F ether3

After 20 seconds after connecting of ether2:
/ip arp> print
# ADDRESS MAC-ADDRESS INTERFACE
0 D 10.10.10.1 xx:xx:xx:xx:27:5E ether1
1 D 172.168.0.2 xx:xx:xx:xx:3B:9F ether3
3 D 10.10.23.125 xx:xx:xx:xx:36:5С ether1
--//-- ether1
25 D 10.10.10.13 xx:xx:xx:xx:73:1С ether1

If :
ip address/
add address=192.168.1.1/32 interface=ether2

A result in /ip arp> print is similar

help me please

Really for whoever does router look 2 ethernet cards in one network (svich)?

I'm not sure what exactly you want to do.

You can bridge ether1 and ether2, if that is what you mean by "..look 2 ethernet cards in one network (svich)?"

/interface bridge add name=bridge1
/interface bridge port
add interface=ether1 bridge=bridge1
add interface=ether2 bridge=bridge1

/interface bridge add name=bridge1
/interface bridge port
add interface=ether1 bridge=bridge1
add interface=ether2 bridge=bridge1

Thank you greater that answered.
If to create bridge I will have 2 IP address and only 1 MAC (mac address of bridge). I will connect a network cable only in one network card.
I want what in a network there was router from 2 MAC and 2 IP. I want users to connect on two interfaces (for example PPPOE). IP can or in one or different ranges.

two interfaces from the same router connected to a switch can cause loop in the network (the network can be down).
if you want to run 2 PPPoE service with different profile, it can be done on one interface.