Biometrics Sub-class 600 Visitor Visa

I applied for visitor visa sub-class 600 for myself and family. I have travelled to Australia once before but my family didnt. Right after applying online, myself and my kids got the biometrics VLN and it shows in the system with bar code. For my wife, there is a letter with VLN code for biometrics but on the account, it says:

No further action is required from the applicant at this time.

The Department will send a further request if any additional action is required from the applicant to meet the biometrics requirement.

Also, when I tried to book biometric appointment, it didnt work for my wife and VFS appointment site shows the message:

The vln number is already used for another application. kindly provide a unique vln number.

Anyone faced similar situation and what actions were taken? How do we do the biometrics for my wife since the VFS appointment is not accepting it. Is it some glitch in the system or what? Any guidance would be appreciated. Thanks.