Connector Plug and Receptacle keying.
Avoid using the same Plug and Receptacle pair on the same panel or test system.
If for some reason you need to use the same physical dimension consider a family of connector that have keying capabilities
Keying can be via build-in or some part added to the connector so only the matching Plug/Rect can connect.
Using different physical dimension connector is also a great way to prevent connecting mishap.
ex using 9pin D connect pair and 15pin D connector pair
Side note
Higher end connectors may have long lead time(time from ordering to part arriving) alway ask for stock info.
Keyed connector (non default keying) my be harder to find in-stock.
Test Engineers Resource 