I am working hard on my English,so excuse me if the sentences are poorly organized!

NO LOG FILE! - setting up server logging...
[2020-01-19 00:39:54 INFO] Starting Server
[2020-01-19 00:39:54 INFO] Version 1.14.1.4
[2020-01-19 00:39:54 INFO] Session ID 6e479d59-22e4-46d8-a84e-c02d55ed97f1
[2020-01-19 00:39:54 INFO] Level Name: RUNNINGWORLD
[2020-01-19 00:39:54 INFO] Game mode: 2 Adventure
[2020-01-19 00:39:54 INFO] Difficulty: 0 PEACEFUL
[2020-01-19 00:39:55 INFO] IPv4 supported, port: 25565
[2020-01-19 00:39:55 INFO] IPv6 supported, port: 65535
[2020-01-19 00:39:55 INFO] IPv4 supported, port: 19132
[2020-01-19 00:39:55 INFO] IPv6 supported, port: 19133
[2020-01-19 00:39:55 INFO] Server started.

The "port" lines appeared for two times with the second one using default port,after which I started another server at the same time whose port was set to be different and only to find the "port" being occupied like this:

NO LOG FILE! - setting up server logging...
[2020-01-19 00:48:36 INFO] Starting Server
[2020-01-19 00:48:36 INFO] Version 1.14.1.4
[2020-01-19 00:48:36 INFO] Session ID 28f22195-e3fe-4591-aee6-e8770afd384d
[2020-01-19 00:48:36 INFO] Level Name: Bedrock level
[2020-01-19 00:48:36 INFO] Game mode: 1 Creative
[2020-01-19 00:48:36 INFO] Difficulty: 0 PEACEFUL
[2020-01-19 00:48:37 INFO] IPv4 supported, port: 0
[2020-01-19 00:48:37 INFO] IPv6 supported, port: 0
[2020-01-19 00:48:37 ERROR] Network port occupied, can't start server.

The former server is accessible with the "25565" IPv4 port but not default ports,while the latter one is just not accessible at all.