Yes they can be programmed and you can had 3 keys. 1:master. You already had. 2: slave key. Secondary key. 3: Backup key. The third and final.
Source the transponders used one and they can be easily programmed through Toyota original scan equipments. Note. Universal scan equipments are not worthy enough to properly register the slave and backup key and also cannot calibrate them so dont fall victim of those sitting in the market...