Hi, I had this same issue. To complicate things a little further, I (the sponsor) am also the representative of my spouse so I had to sign as sponsor, representative and spouse. The IRCC agent I called said I should sign as representative and spouse and then include an explanatory note about the confusion and the fact that they advised us to sign all to be on the safer side. Our application was received on July 9 and we're yet to know if it was okay or not but as at last Firday when we called them they said it's been opened and under review