I do not mean to argue BUT in February we cruised the Dawn. We did our own and had to make our own arrangments for Wyndham OSJ because the Princess allocation was filled. The next morning all of the "Princess people" put their luggage outside their door for pick up and I did notice that their luggage tags were a different color than the tags that Princess issued to us. I am 100% positive about that observation because when I saw that luggage in the hall I thought "gee, we could put ours out too and no one would know the difference". THEN I noticed the tag color and realized that perhaps they would notice! (Actually we prefer to take my luggage to pier myself because then we know without a doubt that luggage arrived at pier.)
Princess offers the choice of 3 hotels in San Juan. My guess is that to differentiate between those pre cruise hotels - that different color tags are given to the passengers based on hotel package. In this case, the hotel is their first "princess destination". Everyone else gets a color tag that indicates the ship is the first official Princess destination.