I am not explaining myself well. Perhaps it may be hard to understand unless you have used such a system.
In a transfusion service, like a hospital, the BB armband number (regardless of the name or other information on the label) is placed on the specimen when it is drawn. That number goes into the BB computer system when the type and screen and other testing is done. If a product is ordered, that BB number is on the tag on the unit. When it is issued from the blood bank, that number must be on the request form brought to the BB--otherwise no issue no matter what information matches up. (Of course, name, birthdate, etc. must match also.) When the unit reaches the patient, the BB number on the unit tag must match the BB number on the BB armband which is on the patient. Its a full-circle kinda thing. The unit is very unlikely going to go to the wrong patient--no matter how they are otherwise ID'd--if a strict BB number and armband system is used.
With such a system, which is relatively common I think, the patient can come in and be under a false ID, and still get appropriately matched blood products. One cannot say this for a system that only depends on two separate draws for assurance that an electronic XM is appropriate. If the wrong patient is drawn once for some reason resulting in WBIT (like in the wrong bed in a room)--the same circumstances can cause the second draw to be WBIT. Then if the unit goes to another patient---well, that's when the God Help us comes in!
Scott