edges_found and edges_covered mismatch

[harrison4ride]

Hi all,

I am using aflplusplus and a custom afl++ fuzzer to do the experiment.
During fuzzbench experiment, afl++ will generate plot_data record:
# relative_time, cycles_done, cur_item, corpus_count, pending_total, pending_favs, map_size, saved_crashes, saved_hangs, max_depth, execs_per_sec, total_execs, edges_found
Fuzzbench will use snapshot to evaluate the fuzzer performance recording: ,git_hash,experiment_filestore,experiment,fuzzer,benchmark,time_started,time_ended,trial_id,time,edges_covered,fuzzer_stats,crash_key,bugs_covered

And I found in the same experiment, edges_found is less than edges_covered. Any idea why?
Additionally, the edges_found in custom_aflpp is higher than edges_found in aflpp, but edges_covered in custom_aflpp is less than edges_found.
Here is the shortcut of raw data:
plot_data of custom_aflpp:

Relative Time	Cycles Done	Current Item	Corpus Count	Pending Total	Pending Favs	Map Size	Saved Crashes	Saved Hangs	Max Depth	Executions Per Second	Total Executions	Edges Found
50398	23	128	1699	232	0	27.35%	0	0	13	4849.04	304726213	1588
50403	23	107	1699	232	0	27.35%	0	0	13	5302.55	304753210	1588
50408	23	1036	1699	232	0	27.35%	0	0	13	5249.57	304779127	1588
50413	23	1093	1699	232	0	27.35%	0	0	13	5162.56	304807198	1588
50418	23	107	1699	232	0	27.35%	0	0	13	4887.70	304831321	1588

plot_data of aflpp_baseline:

Relative Time	Cycles Done	Current Item	Corpus Count	Pending Total	Pending Favs	Map Size	Saved Crashes	Saved Hangs	Max Depth	Executions Per Second	Total Executions	Edges Found
56686	611	1673	1913	16	0	26.73%	0	0	15	16005.00	896729564	1552
56691	611	821	1913	16	0	26.73%	0	0	15	15045.84	896808391	1552
56696	611	366	1913	16	0	26.73%	0	0	15	16217.05	896887749	1552
56701	611	1473	1913	16	0	26.73%	0	0	15	16599.39	896977824	1552

Edge covered of custom_aflpp:

Relative time	Trial_id	edge_covered
45900	28	1978
46800	28	1978
47700	28	1978
48600	28	1978
49500	28	1978

Edge covered of aflpp_baseline:

Relative time	Trial_id	edge_covered
54900	13	2000
55800	13	2000
56700	13	2000
57600	13	2000