I have the following dictionary, that consists of Keys: list of tuples as values

```
{0: [(1410.0, 21.77562368178597), (1400.0, 19.207664561646514), (1400.0, 0.0008002910625641847), (1390.0, 0.005384339399360756), (1390.0, 16.81119144715727), (1380.0, 0.006317587214078991), (1380.0, 14.581397723675186), (1370.0, 12.425676833176958), (1360.0, 10.157186391679849), (1350.0, 8.464056857473565), (1340.0, 6.743908971063571), (1330.0, 4.886783322196731), (1320.0, 3.712576730302521), (1310.0, 2.689847385668083), (1300.0, 1.6219146729959537), (1290.0, 0.41216337921204677)], ....etc)

```

In some cases there are tuples that have same first element but different second element.
In the example from the code above `(1400, 19.2)` & `(1400, 0.0000000000291)`

What I want to do is to combine these tuples into one tuple (1400, (sum of the second element)