Remove duplicate entries from calc_dispatch per carrier and avoid war…

…nings

There were entries for each generator (assuming that there is only one generator
for each bus and carrier). But when redispatch is eplicitly considered, there are
up to three generators for each combination. To avoid duplicate entries, only
unique combinations are used as an index for the series

etrago/analyze/plot.py

@@ -841,16 +841,18 @@ def calc_dispatch_per_carrier(network, timesteps, dispatch_type="total"):
     ]
 
     dist = pd.Series(
-        index=pd.MultiIndex.from_tuples(index, names=["bus", "carrier"]),
+        index=pd.MultiIndex.from_tuples(
+            index, names=["bus", "carrier"]
+        ).unique(),
         dtype=float,
-    )
+    ).sort_index()
 
     for i in dist.index:
         gens = network.generators[
             (network.generators.bus == i[0])
             & (network.generators.carrier == i[1])
         ].index
-        dist[i] = (
+        dist.loc[i] = (
             (
                 network.generators_t.p[gens].transpose()[
                     network.snapshots[timesteps]