sap same external handling unit number with two hu identfier types

1. HU02 Input the hu number 1256392 ,then click the save button.

2. HU02 click the automatical button, it will generate another 1256392 again.Click the save button, it will display successful message.

We met issue as below:

1, When we create a transfer order for this material, if we input the HU it will popup HU wrong.

2, when VL74 print the hu label ,it couldn't identify .So it often prints wrong label.

So how to avoid the same external handling unit issue? Thanks