Balance S390-30

Hello
I ordered 8
S390-30 - 30" Series 390 Channel Balance
Option: 2965
to replace 2964 window balances
I installed 4. but they are much too strong.
It turns out that they have a double spring inside of them instead of a single spring like the old one.
I could not see this in the website picture
the windows shoot up now, instead of getting pushed up, and are hard to close.
what should I do?
can I remove the inner spring?
should I return them, and get a different one?
they fit perfectly, but they are too strong.

Thank you


The size and shape of the channel and ends are exactly the same as the ones I ordered
The only difference is the double spring

the bottom measurement is exactly like that (1-1/8")
There is an inner spring here. Is there a way to remove it?
Is there an identical part with only one spring?
Thank you

I didn't weigh it on a scale
But it weighs about 60 pounds
It has 4 balances on each window