Fitting new leisure battery

Just fitted a new leisure battery but its instructions say to remove both travel bungs at front and back. This would mean one vent would not have a breather tube through the floor. Does anyone know if this is really necessary? The last battery only had one plug removed, can I assume this is the correct way to do it?
Thanks

I left one bung in, as don't want Hydrogen entering the Cab area.

You only need to remove the one bung to fit vent tube, I thing there are two so you can fit tube to the most convenient side .Fumes could come in if you remove the other one.You will see AS only fit one tube and leave the other bung in .