When we go back in such episodes 901 902 , we have a hint that you may conclude the writer of 2 messages are different when there is difference in manner of writing , such as writing a comma by Eri Kisaki .
Rum sent two messages to Bourbon asking him to investigate Kudo Shinchi ,,, but when you carefully examine the two messages , we conclude the way is written in both is different , so may be the writer of the two messages are different , which means there is another person who may use name of RUM at sometimes .
The first message from Rum to Bourbon was in Chapter 1008 ,,, in that chapter also we knew Karasuma ,,, so I think the first message to Bourbon was from Karasuma / Rum / Chikara Katsumata .
While the second message was in chapter 1011 , in that chapter the girls were dressed as Rabbits , so this might be a hint that Wakita who looks like Rabbits was the one who sent that second message to Bourbon .
Maybe RUM / Chikara who ordered Wakita to do that . it seems Wakita is the organization's spy hunter , Wakita was able to reveal Akai's cover as an FBI agent , so I think also he is the one who exposed Scotch's cover being an NPA agent , and now it's Bourbon's turn because Chikara / RUM doubts him . So Chikara ordered Wakita to watch Mouri Kogoro and also watch Bourbon .
There are few different details that I noticed in the two messages :
1- The sentence " time is money" in the first message written in the middle of speech , while in the second message at the end .
2- Rum signature is very far from speech in first message , meaning there is a big break between it and speech , while in second message , the signature is close to speech .
There may be some other differences , but it seems that Wakita is a very close assistant to Rum as Wakita hinted in his first appearance when he talked about hint of Yaiba , but real RUM/Chikara we know is the one who actually has a left prosthetic eye and a very secret identity .
Another note that may be important , but it hasn't relation with the current chapters :
In chapter 344 , Agasa was talking as a flashback about Sharon's Vineyard fake funeral , there was an old man painted so clearly in that flashback .... Who do we have here , Karasuma Renya ??
Bourbon said at beginning of arc RUM that there is a relationship between Vermouth and the boss , so the relationship i expected between Rum / Karasuma / former boss and Vermouth may be she is his daughter .