evidence of what? two separate strains?
this paper mentions two strains[0], 'L' and 'S' type, was it refuted?
[0]: https://academic.oup.com/nsr/article/doi/10.1093/nsr/nwaa036...
this paper mentions two strains[0], 'L' and 'S' type, was it refuted?
[0]: https://academic.oup.com/nsr/article/doi/10.1093/nsr/nwaa036...
See: https://nextstrain.org/ncov/global
There is pretty much no evidence of what common people would call "multiple strains" - as in, immunity doesn't transfer, different infection characteristics, etc.
The paper you posted was debunked pretty much instantly by people that know what they're talking about. There's a lot of junk papers out there written by people on coronavirus that aren't even in the field.