There are 2 rows of parallel contacts in a straddle mount USB connector ( male or receptacle ). Generally speaking, contact numbers of them are the same. They are symmetrical.

For example , please see following picture of our USB Type C  plug 24 Positions (both 12pos for row 1 and row 2 )  :

And straddle mount means that PCB board edge is placed in the middle of row 1 and row 2 contacts .  Row 1 contacts will be soldered on top side of PCB, while row 2 contacts will be soldered on bottom side of PCB. Since We have 0.8mm & 1.0mm thickness board , the USB contacts distance can be customized to fit differentc thick PCB board

like picture as below ( bord edge mount USB type C plug )  :

Jinbeili Electronics straddle mount type USB connectors :

https://www.jbl-ec.com/usb-31c-f-j01-usb-type-c-24pins-splint-typeusb-c-female-connector-product/

https://www.jbl-ec.com/usb-31c-m-j01b-008-board-edge-usb-type-c-plug-24pin-usb-3-2-gen-2-usb-c-product/

https://www.jbl-ec.com/usb-c-3-1-female-connector-clip-type-1-0-l9-3mm-usb-buchse-splint-usb-31s-f-01-product/

https://www.jbl-ec.com/usb-3-1-type-c-connector-24-pin-dc30v-1a-with-side-slot-support-usb-c-socket-splint-1-0-usb-31c-m-j10a-product/

https://www.jbl-ec.com/usb-3-0am-j08-usb-3-0-type-a-plug-9pin-male-connector-dip-usb3-0-usb-a-product/