Just completed a 4/8 o-27 layout for grandson. Will it increase the current if I add another lock-on.
Adding another lockon next to one you’ve already got there won’t anything EXCEPT a more solid connection. If you have a fairly large layout of sectional track-- say a loop with 26 of 38 or 50 sections of track (yes, that’s big!) you could loose power at the sections distant from the lockons if you track pin connectors are making less than perfect contact. Wire makes a better electrical connection than a bunch of sections of track.
I don’t know if on a 4x8 it would makes that much difference. Adding another lockon will NOT add another x number of volts to the track circuit if both lockons are being powered from the same transformer circuit. Just make better connection.