Mikrotik Dual WAN [pppoe-client] PCC with PPPoE Server

Make sure you change the interface name accordingly. In this example I have 3 interfaces.
ether0  (named as Local) is connected with Local LAN users.
ether  1   &   2  (named as WAN1 & WAN2) are connected with ISP WAN switch.
Also change the user name passwords in the pppoe client section, or create manually via PPP/Interfaces
PPPoE users IP pool is 172.16.0.0/16 (internet is allowed for this series only means when the user will be connected via pppoe dialer, he will be able to use internet)

# Setting up INTERFACES names for our comfort

/interface ethernet
set 0 name=Local
set 1 name=WAN1
set 2 name=WAN2

### Adding PPPoE Client connections for each WAN interface, Make sure to change it or add via GUI

/interface pppoe-client

add ac-name="" add-default-route=no allow=pap,chap,mschap1,mschap2 dial-on-demand=no disabled=yes interface=WAN1 max-mru=1480 max-mtu=1480 mrru=disabled name=pppoe-out1 password=hahaha \
profile=default service-name="" use-peer-dns=no user=user-1
add ac-name="" add-default-route=no allow=pap,chap,mschap1,mschap2 dial-on-demand=no disabled=yes interface=WAN2 max-mru=1480 max-mtu=1480 mrru=disabled name=pppoe-out2 password=hahaha \
profile=default service-name="" use-peer-dns=no user=user-2

### Starting the MANGLE MAGIC PCC SCRIPTING START Here
/ip firewall mangle

add action=accept chain=prerouting disabled=no in-interface=pppoe-out1
add action=accept chain=prerouting disabled=no in-interface=pppoe-out2

add action=mark-connection chain=prerouting disabled=no dst-address-type=!local new-connection-mark=wan1_conn passthrough=yes per-connection-classifier=both-addresses-and-ports:2/0 src-address=172.16.0.0/16
add action=mark-connection chain=prerouting disabled=no dst-address-type=!local new-connection-mark=wan2_conn passthrough=yes per-connection-classifier=both-addresses-and-ports:2/1 src-address=172.16.0.0/16

add action=mark-routing chain=prerouting connection-mark=wan1_conn disabled=no new-routing-mark=to_wan1 passthrough=yes src-address=172.16.0.0/16
add action=mark-routing chain=prerouting connection-mark=wan2_conn disabled=no new-routing-mark=to_wan2 passthrough=yes src-address=172.16.0.0/16

### NATTING both WAN connection for PPPoE IP Pool users only

/ip firewall nat
add action=masquerade chain=srcnat disabled=no out-interface=pppoe-out1 src-address=172.16.0.0/16
add action=masquerade chain=srcnat disabled=no out-interface=pppoe-out2 src-address=172.16.0.0/16

### Setting Default Routes for MARKED packets for both WAN and for local router use. (zaib)

/ip route
add check-gateway=ping disabled=no distance=1 dst-address=0.0.0.0/0 gateway=pppoe-out1 routing-mark=to_wan1 scope=30 target-scope=10
add check-gateway=ping disabled=no distance=1 dst-address=0.0.0.0/0 gateway=pppoe-out2 routing-mark=to_wan2 scope=30 target-scope=10
add check-gateway=ping disabled=no distance=1 dst-address=0.0.0.0/0 gateway=pppoe-out1 scope=30 target-scope=10
add check-gateway=ping disabled=no distance=1 dst-address=0.0.0.0/0 gateway=pppoe-out2 scope=30 target-scope=10