What to do with extra basic chargers?
I have 3 standard, and one quick charger. I have 2 of the 3 standard and the one quick charger mounted in my garage for charging my 4 batteries. The 3rd standard charger will hang out in my travel trailer for when we are on the road and I take the inverter and a 2.5 ah battery with us to run the inverter. I'll have the charger to charge the battery when needed. And have the inverter to run my laptop, among other devices, when boondocking in the trailer.
I have 3 standard chargers and 1 rapid charger. I keep 2 standard chargers in the garage "all year round" to charge my batteries during mowing season. The other 2 chargers are in the house, for when I need to charge my batteries. So yes, keep them for when you need to charge 2 or more batteries at one time, or when one of the charges fails on you ... :-)