Using unique non clustered index with unique clustered index Would there be any scenario where it would make sense to create a unique non clustered index that includes a column that is contained in a unique clustered index?

In other words, if I have a Products table with a unique clustered index on the ProductID column. Would there be an acceptable scenario where I would need to create a unique non clustered index that includes the ProductID column in addition to a couple of other columns, or, would the mere inclusion of the unique ProductID column make creating the non clustered index unique irrelevant?
Yes having a column in multiple unique keys is sometimes perfectly reasonable.  In the case that you gave above I'm not sure I would bother since the ProductId key is unique regardless.  But let's say that you have a product table like this:

ProductVendor  PK
ProductCode  PK
ProductDescription
.....


In this particular case the ProductVendor and ProductCode are together unique and are your primary key and clustered index.  However there is an additional business rule that ProductDescription must also be unique by ProductVendor.  In this case you could create a non-clustered index on ProductVendor, ProductDescription.