So if I get you right, 1.1.1.1 and 2.2.2.2 are not just L2TP servers but general purpose servers?
If so, you’ll need to use policy based routing - mark packets to UDP port 1701 with a specific routing-mark using /ip firewall mangle rules, and create the two route-pairs above with that routing-mark.
/ip firewall mangle
add chain=output action=mark-routing protocol=udp dst-port=1701 new-routing-mark=l2tp
/ip route
add routing-mark=l2tp dst-address=server1 distance=1 gateway=gw1
add routing-mark=l2tp dst-address=server1 distance=2 type=blackhole
add routing-mark=l2tp dst-address=server2 distance=1 gateway=gw2
add routing-mark=l2tp dst-address=server2 distance=2 type=blackhole
If you use fasttracking, the whole task becomes slightly more complex, see details here.
But if the Mikrotik itself does not need to contact the two servers for anyting but the L2TP tunnels, you can use /ip route rule to choose the routing table upon src-address and dst-address combination instead of the mangle rule. Route rules do not interfere with fasttracking.