I am pretty sure there is one but I do not know how to do it.
If you are using the EC you can do it by opening up the config files for both characters in your favorite text editor, find the macro in the source character's file, copy it, locate the macro area in your destination character's file, then paste the macro.
If you are using CC then do a search on your computer for the character name you want to copy the macros from. It will be a text file called macros2d under your character name.
It will be found in something like UO --> Shard Name --> Character name --> macros2d.txt.
Open this notepad doc and copy it all. Then do a search on the character you want to copy to macros to and look for the macros2d file (the character needs to be logged out for the changes to save). Paste over the macros and then save and close the text file.
Your macros (in game) will now be on that character too.
Hope this helps.