My still new to me 2003 4R only came with one key and one fob, so I needed some spares. Fortunately, the one key is a master.
I bought 2 of these remotes after reading thru this thread - Upgraded Flip Ker Remote for Toyota keyless entry clicker fob HYQ12BBX DOT CHIP | eBay
Took the blanks to my local Toyota dealer and ended up buying another spare original key while I was there since they only charged $30 for them. They were able to cut the new key and both the flip blanks using the key code. $32 out the door with tax.
Got home and I was able to successfully program the new Toyota key and one flip fob for the immobilizer chip. I guess it will only take 3 total. I was also able to program the flip fob remote for lock, unlock and to open the hatch window.
I have been trying to reprogram the fobs to unlock all doors with a single press but haven't been able to do that successfully. I like the flip fob tho. Not too bulky and everything on it works as it should. Getting the roll pins in was a pain tho.
I think you can program up to 4 or 5 fobs and keys, I hit the limit too and had to erase them all and then add them back in. Its pretty easy.