Nope, I'm afraid the Rm2k3 images are different. Rm2k uses monsters facing front, while Rm2k3 uses monsters facing to a side. This is because of the different battle systems. Rm2k3 monsters look a little more 3D-ish too.
Anyway, I have the Rm2k RTP on my PC. Just in case I need something from it. There is no monster called Hell Knight, but Dark Elf is here. There's a monster called Dark Knight tho, I have a feeling you mean that one. So here they are, let me know if they are the right ones or not.