Well if you have P5 you can use the material color math multiply. You can add the two bump maps together by setting to color for each color_math channel to white, point the channel;s to each bump then set the operation to multiply. That's one way. Another way is to make use of the bump and gradient bump channels. Put one bump on one channel and the other on the other channel. A more elaborate way is to use the color_math and the transmap with multiply to cut the medallion portion from the medallion map then use the inverse of the transmap to cut the non-medallion portion from the other map. Then add the two together.