Infinty IRS Delta woofer cable connection

I have Infinty IRS Delta speakers.
It has 2 woofers in a box.
I took off these woofers then check cable connection inside.
Bottom woofer is connected normally,but top woofer is connected opposite plus and minus. I am not an original user,I got used one. So I can not know this connection is collect or not. If somebody knows about it, please let me know.

Looking at page 3 here, there is a jumper wire between the plus of the control woofer and the minus of the slave woofer. Then referring to page 2, the minus of the control woofer and plus of the slave woofer are connected to the crossover, so woofers are wired in series. Sounds like they are correct, as the color of that jumper wire will be connected to plus of one woofer and minus of the other.