Yes, you can use the same Account ID on multiple devices.
To log into an existing Account ID on desktop:
- Download and install Session on your new computer
- Open the Session app, but instead of creating a new Account ID, click I have an account
- Enter your recovery password into the text field provided and choose your display name if one had not been previously set.
- Done!
To log into an existing Session ID on mobile:
- Download and install Session on your new device
- Open the Session app, but instead of creating a new account, tap I have an account.
- Enter your recovery password into the text field provided
- Chose your notification preferences.
- Enter your display name if one was not previously set and tap Continue
- Done!
Your additional device should now sync with your first device, and both devices should be able to send and receive messages from the same Account ID.