dont treat components with a subset of other a larger components' subcomponents as equal to the bigger component

src/icalendar/cal.py

@@ -437,6 +437,9 @@ class Component(CaselessDict):
         return f"{self.name or type(self).__name__}({dict(self)}{', ' + subs if subs else ''})"
 
     def __eq__(self, other):
+        if not len(self.subcomponents) == len(other.subcomponents):
+            return False
+
         properties_equal = super().__eq__(other)
         if not properties_equal:
             return False

src/icalendar/tests/calendars/issue_526_calendar_with_event_subset.ics

@@ -0,0 +1,11 @@
+BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:icalendar-2023
+BEGIN:VEVENT
+UID:1
+SUMMARY: Some event ':'
+DTSTART;TZID="Western/Central Europe";VALUE=DATE-TIME:20211101T160000
+DTEND;TZID="Western/Central Europe";VALUE=DATE-TIME:20211101T163000
+DTSTAMP:20211004T150245Z
+END:VEVENT
+END:VCALENDAR

src/icalendar/tests/test_unit_cal.py

@@ -469,6 +469,7 @@ class TestCal(unittest.TestCase):
         'issue_178_custom_component_inside_other',
         'issue_526_calendar_with_events',
         'issue_526_calendar_with_different_events',
+        'issue_526_calendar_with_event_subset',
     ], repeat=2)
 )
 def test_comparing_calendars(calendars, calendar, other_calendar):