Title says it all, to my knowledge these are spells that only a light domain cleric would have access to iirc. I just want to make sure this is a bug before I tell him that bad news. Fireball is on the manage spells list for him to pick from, it's even listed twice for some reason. Burning hands is there too.

There might be something more going on. Are you comfortable with posting the url to the character sheet so someone can take a look?

Id also say that if the spells are showing up multiple times, that probably has something to do with something homebrew someone has done. One of the often things that people do to get around certain homebrew restrictions is to make a duplicate without the restrictions. Someone (or a few) people may have a homebrew version of those spells in their homebrew collection.

https://www.dndbeyond.com/characters/13430428

Here's his sheet, I made another loxodon grave cleric and brought him to 6th level and there was no fireball. My guess it since he made this character over two years ago some things got bugged as dndbeyond updated the character sheets overtime. (He unprepared the spell so you won't see it under his spell list rn.)

Martyr is a homebrew weapon that may be giving them access to those spells accidentally, depending on how it was made.

Given that there is the use of homebrew on the character I would guess that someone in the campaign has a homebrew version of fireball and burning hands that they have made available to all clerics. Unfortunately, homebrew is shared throughout a campaign regardless of content sharing and cant be disabled so you'll just need to make sure the player doesn't take things they shouldn't have or you can check if something they have is homebrew by clicking on it and instead of having a listed source it will say Version instead. 

Hmmm, I made Martyr myself and it only added aid as a spell to be cast through the item. I'll ask him and my other players to check their own homebrew creations, maybe it's on their end because I went through my collection and saw no spell copies.

They can remove it from their collection and it should go away from the other's character sheets, but not from their character sheet if they already have it on their sheet. As long as they don't remove it from their sheet they should still have access to it. They can always add it back if they need to. 

Oddly enough, none of my players have any homebrewed spells in their collections or creations, the cleric is just going to ignore those spells going forward. I appreciate the help nonetheless.

Interesting. Could you have the player add the spells back to their character sheet so one of us can look at it and potentially see where it came from?

Sure thing, I just added fireball and its duplicate.

Both of the spells are homebrew. If you click on them on the character sheet it says Version where it should say the source. If no one in your game knows where these have come from (like you said) you can just have the player ignore them. 

Very odd, I'll have them double check to make sure. Thanks again for the help!

Of course! Glad to help! Make sure they check their collection, not their creations. 

Have your players check their Homebrew Collections, and maybe check your own as well just to be sure.

Yep, turned out the cleric had a fireball from 2018 in his collections, he removed it and the spell + its dupe disappeared!