HMC347A-Die v.s. HMC347B

Hi all,

Our customers have used HMC347.
They will consider choosing a replacement product as the stock purchased at the last time buy will be gone.
HMC347A-Die and HMC347B are both dies, and there is a difference between suffixes A and B.
I do not know why there are two types of devices with equivalent specifications,
The slightly difference between them can be confirmed to some extent in size and electrical specification.

Which is the best choice for HMC347A-Die and HMC347B when considering replacing HMC347?
Please advice to us.

Best regards,