Changing Energy-meter but want to keep old readings

I’ve had a Shelly 3EM for a while which I’ve added to my Home Assistant so I can see all my data under the Energy Dashboard.

I recently changed to a SlimmeLezer since my incoming power meter supports this.

They both work great but I ran into a problem when I removed the Shelly 3EM from the Energy dashboard and added the SlimmeLezer. I only see the data from SlimmeLezer now.
If I add the Shelly back to the Energy Dashboard I can see my old values again but they are overlaping so I get a double reading during this period.

Since I want to move my Shelly 3EM to monitor my pool I would want to somehow change so the historical values of the Shelly is associated with the SlimmeLezer instead (or a dummy device or whatever) so I can see all my historic data.

Is the energy data stored in the SQLite home-assistant_v2.db database or somewhere else? And how would I accomplish this?