Pandas dataframe groupby and then sum multi-columns sperately
IIUC:

In [5]: (df.groupby("Groups", as_index=False)
           .agg({"Date":"first", "data1":"sum", "data2":"sum"}))
Out[5]:
  Groups      Date  data1  data2
0    one  2017-1-1      6     33
1    two  2017-1-2      9     27