Unexpected and unclear labels' grouping in the legend when using plotly(js) backend with subplots

Specific Domains Visualization
,
1 
begin
	using StatsPlots

	gr()
	# pgfplotsx()
	# plotlyjs()
	# plotly()
	
	serie1=rand(5)
	serie2=rand(5)
	serie3=rand(10)
	serie4=rand(10)
	
	pg = plot(
	   plot([serie3 serie4], label=["Serie1" "Serie2"]),
	   plot([serie3 serie4], label=["Serie3" "Serie4"]),
	   layout=(1,2), size=(600,300), grid=:off,
	   left_margin = 5Plots.mm
	)
	#savefig(pg,"test.pdf")
end

gives

image
image1912×1748 277 KB

so far so good.
Also pgfplotsx() is fine but if I want to use plotly() (or plotlyjs()) I get
image
image1994×1730 271 KB

with all the labels grouped together which makes it ambiguous.

Why the different behavior?
Any suggestions to “fix” the plotly case?

2

The plotly() backend might be hopeless for this task - see this Plots.jl issue.

3

Thank you for the link.