Organization A have a driver named SomeDriverName which passed WHQL signing.
Organization B submitted a WHQL signing with the same driver name SomeDriverName. Will Microsoft accept the submission and sign the driver?
Is it possible to have two drivers with the same drivername submitted to Microsoft for WHQL signing?
Yes.
That’s why it’s important to choose somewhat personalized driver names. “SerialCard.sys” would be a poor choice. 
Also remember that submitting for WHQL does not automatically enroll your driver in the Windows Driver Library, which is what gets searched when you plug in a new device. Microsoft does check that there aren’t two drivers for the same Hardware ID in the library, but they don’t check the driver name.
If you run from driver store the file naming conflict is no longer a problem. But perhaps the service name is…?