I don't think having more than one pillow is a great idea. Any extra ones invariably get tossed onto the floor, left to wallow in clumps of cat fur on the carpet the whole night while the one chosen pillow gets all the attention, basking in the glory of shampooed hair, rosy cheeks, and saliva of the most excellent kind.
But, one may say, you can have two and stack them. I still think no 'cause then the bottom one doesn't get enough air, not to mention the possibility of a crick in your neck the next morning.
Then there are those who collect and hoard pillows. No doubt it's because they formed a habit of it in their teenage years. I say it's a misplaced investment, especially problematic in a marriage. Before he/she even realizes it, he's rolling in pillows as if he's won the lottery entirely by his own efforts and his spouse is without any head support, and that contributes to an overall miserable sleeping atmosphere. In no time, his/her spouse will be fantasizing about a couch cushion which is better left outside the bedroom.
If two people, each with a single pillow, can push them together to form one long pillow unified by the Bed... well, that will make for optimal resting conditions. Or hanky panky, as a matter of course.