A very bold statement and one I have never heard an evolutionist make. In fact, the only example I have heard of discussed is hemoglobin. I would think we need some reference for the above. If they are duplicated genes they need to be the same size and have a fairly similar sequence. Reference?
Wow, where to begin? It is taken as an absolute given in biology that genes are related to each other.
Here are a few reports from the genomebiology website...
A nice analysis of a family of the bHLH transcription factors: http://genomebiology.com/2002/3/6/research/0030/
Mammalian Olfactory (smell) receptors: http://genomebiology.com/2001/2/6/research/0018/
These belong to a huge superfamily of proteins which act as molecular switches in the cell. All of these guys are very similar in size/structure yet they have distinct functions:
http://genomebiology.com/2001/2/5/reviews/3007/?isguard=1
This was just a quick search.
If you are really interested you can BLAST away here:
http://www.ncbi.nlm.nih.gov/BLAST/
...with your gene of interest.