The log printed from terminal is correct:
09:08:24 dhcp,info NOC3-CGNAT deassigned 100.64.4.227 for 76:56:9F:BB:0C:93 Z6250CC
09:08:24 dhcp,info NOC3-CGNAT assigned 100.64.4.227 for 76:56:9F:BB:0C:93 Z6250CC
but in Winbox log it's reversed.
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The log entries probably followed each other with short time difference, small enough to have timestamp (stored with a second resolution) the same. If you'd let winbox show logs without sorting, you'd get them in order as they were recorded. Since you enabled sorting, you get it ... but entries with same timestamp can be sorted randomly.