I got this off of ebay a while back.  The story goes Dr. J was doing a signing at a Toys R Us in Long Island back in the 70's.  The person went to get a picture signed which was personalized and then went back in line and got a second non-personalized autograph.  Both pictures were kept in the same frame all these years with the personalized one in the front, hence the discoloration. 

This signature is slightly different from his more modern day signatures.

Any opinions on the validity of this?  I have attached both pictures for comparison.