The description of the Illusionist’s Bracers (GGR p. 178) states:
A powerful illusionist of House Dimir originally developed these bracers, which enabled her to create multiple minor illusions at once. The bracers’ power, though, extends far beyond illusions.
While wearing the bracers, whenever you cast a cantrip, you can use a bonus action on the same turn to cast that cantrip a second time.
However to me it would seem that the effect provided would not actually allow one to cast multiple minor illusions at once because the description of the spell minor illusion states:
The illusion also ends if you dismiss it as an action or cast this spell again.
Am I missing something or does this magic item not actually allow one to do what its flavour text suggests?