Here's an example character I made to illustrate the problem.

As you can see, this character has three copies of the "minor Illusion" cantrip on their character sheet, granted by race and subclass automatically, even though the third feature that grants the cantrip says this:

Improved Minor Illusion

You learn the minor illusion cantrip. If you already know it, you learn a different cantrip of your choice. The cantrip doesn’t count against your number of cantrips known. When you cast minor illusion, you can create both a sound and an image with a single casting of the spell.

This is similar to the issue I already found with the light cleric, where it grants the "light" cantrip even if the character already knows the cantrip via both race (aasimar) and starting class (celestial warlock).

In most cases having 2 spells listed is just annoying, but in this case and a few others, when you are supposed to be able to pick a different spell, it is an actual mechanical concern.

The DDB dev team is aware of the problem. A fix will probably not be implemented until the character sheets get revamped.

In the meantime, you can at least add an extra spell with a homebrewed feat or item (for the instances whete you were supposed to be able to change it).

I just experienced this when creating a level 3 wizard subclassed in illusion... and it was confusing as hell.  Now I realize it's a bug and I am sort of getting screwed out of a free cantrip spell?

Quote from steviezak >>

I just experienced this when creating a level 3 wizard subclassed in illusion... and it was confusing as hell.  Now I realize it's a bug and I am sort of getting screwed out of a free cantrip spell?

 It is a bug, butnDxJxC provided you a workaround so you don’t have to be “cheated” of your cantrip:  make a homebrew feat or magic item that grants you the cantrip. 

Thanks.  Will try.  But for a newbie person, the system is already quite complex as it is.  Having to do that makes it that much more.

Quote from steviezak >>

Thanks.  Will try.  But for a newbie person, the system is already quite complex as it is.  Having to do that makes it that much more.

Creations>Create Feat

In the dropdown to copy an existing feat, select Magic Initiate (Wizard)

Click "create"

Change the name of the feat and the description; click Save

in the Spells section, click the + to reveal the spells that are part of the feat

Remove one of the cantrips and the 1st level spell

Save the Feat

Then go to your character sheet, make sure homebrew is turned on, and select the feat (Features & Traits in the big box on the right side of the character sheet, then Feats, then Manage feats) . The spell is chosen in the feat itself;  (click on the downward facing 6 ^ to see the selection drop-down)

NOTE:  If you don't have access to Magic initiate, create the feat from scratch, go to the Spells section, set the following fields as noted here:

Spell Levels: Cantrip

Spell Class: Wizard

Ability Score: INT

Leave all the other fields blank.

Save the spell, page and then the feat itself.

Or, if you have a subscription (either hero or master tier) you can add this feat to your collection instead of homebrewing one:

https://www.dndbeyond.com/feats/56284-extra-cantrip-wizard

As a forest Gnome I automatically get the cantrip Minor Illusion. DnD Beyond handled that nicely and added it to my spells without affecting my known cantrips.

At 2nd level when I choose to specialize in the school of Illusion it says "When you choose this school at 2nd level, you learn the minor illusion cantrip. If you already know this cantrip, you learn a different wizard cantrip of your choice. The cantrip doesn't count against your number of cantrips known."

Unfortunately, DnD Beyond didn't give me access to an additional cantrip given that I already knew minor illusion as a forest gnome.

Many thanks,

Rangkemi

This is a very long standing bug that has been reported numerous times.

Right now you can work around it by making a homebrew copy of the subclass and changing the cantrip there. Alternatively, you can use a homebrew feat or item to add the cantrip.

Please know that the team has received your information regarding this issue and are aware this requires attention. This has been entered into our backlog and will be worked on at our earliest availability, in accordance with the suggestion’s priority. Thank you!

consider this another data point. issue remains