Will it be a problem if two devices have same device address ?? During packet forwarding will it lead to routing profile error?
No it will not, as long as both devices have a different AppKey / NwkSKey (ABP). LoRa Server stores the device-sessions using the DevEUI. When one DevAddr resolves to multiple DevEUIs, it will try to validate the MIC using the NwkSKey of each device-session.
What if two devices within the same application have same device address?
This is not recommended and you might run into issues.
@brocaar Since having same devAddr is not recommended, does OTAA activation guarantee we will always get unique DevAddr for every device?
I’m currently working on a provisioning system to be used for our devices manufacturing. We are using ABP and the provisioning system will use the Application Server’s API to create devices and keys.
I would like to know how we can be sure that two devices doesn’t share the same Device Address ?@brocaar, you told that it’s not recommended to have the same device address, but is it proof to use the /api/devices/{dev_eui}/getRandomDevAddr API route to get a truly unique device address ?
I’m a bit confused, since I saw that it’s possible to create two devices in the Application Server share the same set of device address, network session key and application session key.
How can we be sure that we have a unique set of device address and keys ?
Thanks for you help 
Two devices sharing the same device address is supported by ChirpStack Network Server and does not cause any issues (in the early days of the project this was an issue, but this is no longer the case). It is important to make sure that the application key / session-keys are unique per device.