2 wan different speed always lower speed.

Hi to all. I am new to this and i just get the mikrotik RB750.

This is code i use. First wan i have its 60mb/s and second one is 20mb/s. First wlan is on port 1 and second one is on port 2. By default i am connected to wlan1, but the speed is 20mb/s ens-ted of the 60mb/s. When i remove wlan2 i get 60mb/s.

My question is there way to get 60mb/s on the first one and then when that fail to transfer to the 20mb/s.

Here is my code that i use. Fill free to correct me if i do wrong.

/ip address 
add addres=192.168.88.1/24 network=192.168.88.0 broadcast=192.168.88.255 interface=local
add address=192.168.0.1/24 network=192.168.0.1 broadcast=192.168.0.255 interface=wlan1
add address=192.168.1.1/24 network=192.168.1.1 broadcast=192.168.1.255 interface=wlan2

/ip route

add dst-address=0.0.0.0/0 gateway=192.168.0.1,192.168.1.1 check-gateway=ping

/ip firewall nat

add chain=srcnat out-interface=wlan1 action=masquerade
add chain=srcnat out-interface=wlan2 action=masquerade

/ip firewall mangle

add chain=input in-interface=wlan1 action=mark-connection new-connection-mark=wlan1_conn
add chain=input in-interface=wlan2 action=mark-connection new-connection-mark=wlan2_conn
add chain=output connection-mark=wlan1_conn action=mark-routing new-routing-mark=to_wlan1
add chain=output connection-mark=wlan1_conn action=mark-routing new-routing-mark=to_wlan2

/ip route

add dst-address=0.0.0.0/0 gateway=192.168.0.1 routing-mark=to_wlan1
add dst-address=0.0.0.0/0 gateway=192.168.1.1 routing-mark=to_wlan2

/ip dns

set allow-remote-requests=yes \primary-dns=8.8.8.8,secondary-dns=208.67.220.220