There are a few things you can try to fix the issue of sound coming from speakers and headphones at the same time:

1. Check the audio settings on your device. Make sure that the headphones are set as the default audio output device. You can usually do this by going to the sound settings on your device and looking for a section called “Output”.
2. Restart your device. This can often fix minor software glitches that may be causing the issue.
3. Update your audio drivers. Outdated or corrupted audio drivers can cause a variety of audio problems. You can usually update your audio drivers by going to the website of your device manufacturer or the website of the manufacturer of your sound card.
4. Try a different pair of headphones. If you have another pair of headphones, try connecting them to your device to see if the issue persists. If the issue does not occur with the other pair of headphones, then the issue is likely with your original pair of headphones.
5. Disable Stereo Mix. If you are using a Windows device, try disabling Stereo Mix. Stereo Mix is a feature that allows you to record audio from your computer’s speakers. To disable Stereo Mix, right-click on the speaker icon in the system tray and select “Recording Devices”. Right-click on Stereo Mix and select “Disable”.

If you have tried all of the above and the issue is still persisting, then you may need to contact the manufacturer of your device or the manufacturer of your sound card for further assistance.