Heraldic courtesy Wikipedia
Heraldic courtesy or courtoisie is a term used in heraldry when two arms are combined next to each other. The dexter arms is mirror-imaged so its charge is turned towards the sinister arms, out of courtesy. This is usually done, when the arms are showing an alliance.
This placement of two arms next to each other is often used in German armorial practice, while in English heraldry impalement is more usual.