Marsd/Ygor,
Thanks for the reply.
Marsd, you are correct on field 2 fileA must match first triple colon delineated segment of fileB.
Ygor, your awk works but if I use the output file as the the new fileB and use same fileA, I get dups. For example:
file1234.us:::uka:ttk:B5432CB:B5432CB...