Do the Fire Elemental's Fire Form trait's and Touch attack's ongoing fire damage stack with each other?

Question

Inspired by the following:

• Does the Fire Elementa's Touch attack's ongoing damage stack with itself?

I realized that my own answer to that question hinges on the idea of features having the same name, but the Fire Elemental actually has two different features that cause extremely similar effects.

Notably it has the Fire Form trait and the Touch attack which state:

[...] In addition, the elemental can enter a hostile creature's space and stop there. The first time it enters a creature's space on a turn, that creature takes 5 (1d10) fire damage and catches fire; until someone takes an action to douse the fire, the creature takes 5 (1d10) fire damage at the start of each of its turns.

[...] If the target is a creature or a flammable object, it ignites. Until a creature takes an action to douse the fire, the target takes 5 (1d10) fire damage at the start of each of its turns.

Do these two ongoing effects stack with each other?

Answer 1

They do technically stack, but a GM can always rule otherwise

Yes, the effects do have different names, and as such, the rules on stacking effects do not apply to these features. Thus a Fire Elemental could enter a creature's space, catching them on fire and causing them to take 1d10 fire damage at the start of their turns and then perform a Touch attack, igniting them again and causing them to take another, separate 1d10 fire damage at the start of their turns.

That is what the rules seem to lay out; however, you may not think this makes perfect sense. After all, the creature was lit on fire twice and a GM could certainly argue that this simply cannot happen and thus the second effect cannot actually occur, but that would be their own ruling. Furthermore, if a GM said that they did stack, they would want to determine how one can go about dousing the fires; does it require one action or two?

Answer 2

The question becomes, does the DM consider the name of the ongoing damage effect to be "on fire" and being an effect of both the two abilities, or is it the effect "Touch" and "Fire Form" with have similar mechanics.

If you consider the effect to be "on fire", then only one applies. If you consider them to be parts of the "Touch" and "Fire Form" features, then they both apply.

In English, something being "on fire" is usually treated as a binary state -- you are either on fire, or not. A situation where someone is "on fire" in 3 different ways at once would be closer to a riddle or a strange exception than plain English. Even something obvious, like "The ship was on fire in 3 places", there is one state that happens to be spread out over 3 spots, not 3 instances of "on fire".

By RAW, it is probably two abilities. The wording even uses "ignites" and "catches fire", there is no common name. However, in practice, the in-world fiction of the two effects seems identical, and 5e intended to be read in natural language.