使用itertools.groupby：

input_dictionary = [{"name":"kishore", "playing":["cricket","basket ball"]},
                    {"name":"kishore", "playing":["volley ball","cricket"]},
                    {"name":"kishore", "playing":["cricket","hockey"]},
                    {"name":"kishore", "playing":["volley ball"]},
                    {"name":"xyz","playing":["cricket"]}]
import itertools
import operator

by_name = operator.itemgetter('name')
result = []
for name, grp in itertools.groupby(sorted(input_dictionary, key=by_name), key=by_name):
    playing = set(itertools.chain.from_iterable(x['playing'] for x in grp))
    # If order of `playing` is important use `collections.OrderedDict`
    # playing = collections.OrderedDict.fromkeys(itertools.chain.from_iterable(x['playing'] for x in grp))
    result.append({'name': name, 'playing': list(playing)})

print(result)

输出：

[{'playing': ['volley ball', 'basket ball', 'hockey', 'cricket'], 'name': 'kishore'}, {'playing': ['cricket'], 'name': 'xyz'}]