Normally, you are not able to put two (or more) candles on top of each other, however, when you break the block you placed them on, they won't break, even when you update them (turning them on ond off etc.).

Some more Details can be seen in the screenshot and in the video

Update: I found the duplicates, I didn't see them before because I never used this bugtracker before and didn't notice that the search bar was set to Bedrock Edition