How to delete duplicated dictionary objects from a List of dictionaries

If any element from the groups of duplicates is acceptable, you could do:

datalist = [
    {'plate': "01", 'confidence': "80"},
    {'plate': "01", 'confidence': "60"},
    {'plate': "02", 'confidence': "91"},
    {'plate': "02", 'confidence': "91"},
]

result = list({ d['plate'] : d for d in datalist }.values())
print(result)

Output

[{'plate': '02', 'confidence': '91'}, {'plate': '01', 'confidence': '60'}]

The idea is to create a dictionary where the keys are values of plate and the values are the dictionaries themselves. If you want to keep the first duplicate entries use reversed:

result = list({d['plate']: d for d in reversed(datalist)}.values())

Output

[{'plate': '02', 'confidence': '91'}, {'plate': '01', 'confidence': '80'}]

Assuming you want to only keep the first duplicated dict found, You can use setdefault():

datalist = [
    {"plate": "01", "confidence": "80"},
    {"plate": "01", "confidence": "60"},
    {"plate": "02", "confidence": "91"},
    {"plate": "02", "confidence": "91"},
]

result = {}
for d in datalist:
    result.setdefault(d["plate"], d)

print(list(result.values()))
# [{'plate': '01', 'confidence': '80'}, {'plate': '02', 'confidence': '91'}]

If you instead want the last duplicates, simply iterate in reverse().

You can use the unique_everseen recipe, also available in 3rd party more_itertools:

from more_itertools import unique_everseen
from operator import itemgetter    

datalist = list(unique_everseen(datalist, key=itemgetter('plate')))

Internally, this solution uses set to keep track of seen plates, yielding only dictionaries with new plate values. Therefore, ordering is maintained and only the first instance of any given plate is kept.