In theory they are the same brand but they came from China. I don’t know if there is a problem with copying or whether there is one factory and lots of resellers. That said, I can’t tell the difference between the open energy ones and eBay but I didn’t do any calibration tests.
I presume you could fit several to the same cable and see what the variation is.
You can look up the ‘known’ devices in the iotawatt documentation to work out what to order. Sct-013-xxx are the ones I chose where the xxx was the appropriate device for the anticipated current.
If buying lots from abroad/eBay it might be worth splitting your orders to make sure you come in under the personal import vat exemption. The delays are more hassle than the vat (and £8 admin charge from the post office)
With IoTaWatt (and OEM stuff as well unmodified) the only model of interest is the SCT013-000 which is a 100A CT. I know there’s a school of thought that a 100A CT is not appropriate for low current circuits, but the SCT013-000 will produce the same results as a 50A CT or a 20A CT when clamped to the same cable with IoTaWatt.
The SCT013-nnn are voltage type CTs with internal burden resistors. They would require modification of the IoTaWatt to use, and moreover, the higher burden causes greater phase shift with no observable increase in accuracy.
The 100A SCT013-000 from OEM should work fine with IoTaWatt and are supported in the configuration tables. If they are still selling SCT006 CTs, I can’t recommend them, although they are also listed in the tables and will work. Both have 3.5mm stereo jacks, as do most all SCT013-000 from Ebay or other sources.