Greetings, iinami, I also had the same issue on my iPhone under iOS 7.0.4, but I found a solution to clear out those dozens of App's purchases which clutter the Updates' window, and they would not go away even after you had already opened the update.
This procedure worked on my iPhone, you may want to give it a try:
1. Go to Settings > General > Date & Time;
2. Turn off "Set Automatically";
3. Click on your date and time (displayed in blue);
4. Set the Month/Year to a year from today (say: "Jan 26, 2015")
5. Exit Settings
6. Now check your App-Store Updates' status
Voila!
You can set your Date & Time back to "Set Automatically". Those Apps will not re-appear.
I have just found this out while I have not had an update since. So, I am not sure, but I have a felling that this will recur on my next update and the next, and so on.
This is either a bug or Apple has set the updated app to go away on a timer. What a waste of time for Apple and for us.
Perhaps Apple could use a little of "if it isn't broken don't fix it!".
I wish you success!