I’ve been using HA for a while and I feel very good but I wanted to understand one thing being new to the home assistant environment; when I install homekit bridge and import HA on homekit I wanted to know I have devices already configured on both homekit and HA but they are also imported into homekit and become double or not?
Thanks
Could you rephrase what you have in mind to do?
Sure I would like to import and use my HA devices in homekit but some are already present in homekit and I wanted to know if importing them were duplicated
TLDR; It could depend on the specifics about the devices in question. In general one has to remove HK devices from HK so that the HA HomeKit Device integration can see the device to take it over. Then to also be able to have HK interact with the same device, one uses HomeKit Bridge to share the device with HK.
Most devices that can only be installed in HomeKit (HK) can be installed in Home Assistant (HA) instead. After a device is installed in HK, removing the device within HK will allow the HK Devices integration to recognize and offer to use the device in HA. This worked for the Aqara presence sensors and the Starling Hub Nests integration so I could automate them directly in HA.
But that left HK unable to control those devices directly (via the HK app or Siri). Enter: HomeKit Bridge.
Using HK Bridge, those devices that were removed could be shared again with HomeKit, like one would with any other device loaded into HA. Voila!
So far, the only device that I have that can’t be removed from HK and installed through HA’s HomeKit Devices integration is my 2 year old Level Lock. It’s simply not recognized (I think there are newer models of Level lock that can).
So that left me able to automate everything in the home via HA, nothing through HomeKit. BUT, the HK app and Siri can do our bidding on those devices as well. (Choosing not to automate anything in HK is just my preference)
I HOPE that was coherent and clear.
Thank you very much for your response, it was very clear. I had already informed myself about the difference between a HomeKit bridge and integrating HomeKit devices directly into Home Assistant. I wasn’t interested in the latter because I didn’t want to remove my devices from HomeKit to integrate them into Home Assistant. At the moment, I find it more convenient to use HomeKit, even for remote management, and it’s easier for my family members who live with me.
My concern was that if I linked and imported devices from Home Assistant to HomeKit, I would end up with duplicate devices or conflicts with the ones already present (e.g., if a thermostat is already in HomeKit and in Home Assistant, I’m worried that it will be imported as a duplicate, or that it might mess up the one already registered in HomeKit after the import from Home Assistant). Thanks"
Same here. I haven’t conquered video with HA so I utilize the HK app for that, as well as using Siri for lights and climate control (despite automations and notifications being setup & executed in HA). WAF is a high priority at home here too. 
Note I’m not committing to a yes or no without knowing the device and how it’s currently integrated. But I don’t see how you can send a device already integrated into HK to HA. I think I tried something like that early on with HA, but it didn’t work out for one reason or another. Details escape me, but nothing was ruined that I couldn’t restore. I would remember a big headache in that regard.
If you don’t have the “Controller for HomeKit” app (found in the App Store), I highly recommend it. One of the many useful features is to backup HomeKit. Having a HK backup along with the HA backup is nice security.
Ok thanks I noticed that a solution to the problem for new devices is to use products compatible with Matter in fact the last purchases I made allowed me to add the device both on homekit and on Home Assistant!