Yes, they did.
Rocket Internet did neither buy nor found CityDeal, but they invested some money into CityDeal and helped it scale in order to become a serious competitor to Groupon. They reached that goal by scaling to 600 employees in just 5 months  and then quickly sold to Groupon for 170m US$ (paid mostly in stock). 
The original founders of CityDeal got leading positions at Groupon CityDeal for the DACH (Germany, Switzerland, Austria) region.  That supports the assumption that they made “some” money from the acquisition.
It’s hard to find actual numbers: The only ones you can find are published when Groupon went public. How much each founder and investor got is buried inside the “dummy management corporations”.