Charging 2 Packs in Series

[TLH101]

I have 2 new identical 4s packs, that will be used together in 8s configuration.
Is it safe to charge these packs in series, as an 8s configuration?
I have a Hyperion 1420i Net3 charger with 2 balance ports. I have charged in series before, but have seen some info that it is bad practice.
Like to hear opinions from those who are experienced with LiPo practices.

[Peter A]

Yes bad practice! But it's your money.

[fweasel]

If you insist on charging 2 packs at once, charge them in parallel with a parallel board. I never charge parallel and do a full balance charge on each pack individually, every time. I love my Hyperion chargers, and use the 720I super duo3 to charge two packs at once. I actually have three of those chargers on my work bench so I can charge 6 packs at a time before an outing.