Is this teak credenza designed by Ib Kofod Larsen or J. Clausen??  

It is Ib Kofod Larsen for Brande.  Model 57J.  
See here (the BM is Brande Møbelindstri, which can be easily verified from marked specimens on the internet):
http://movablemodern.com/documents/617/document-excellent-furniture-comp...
and here (the design credit to Kofod Larsen):
http://movablemodern.com/documents/901/document-%C3%B8nskebo-catalog/pub...

Thank you for the quick responce and the link!!!  I am so happy:D

It is a good looking cabinet. I've always liked them in catalogs. Never seen one in person. 

It is on sale now at Etsy:)

I see. The maker's name really is Brande Møbelindustri, not Brande Møbelfabrik as in your listing. 

Even though it says by Brande Mobelfabrik on the website you linked?