Linestyles look the same in legend

After increasing the linewidth the linestyles in the legend are indistinguishable:

using Plots 
testplt = plot(0:0.1:1, rand(11), label="dashdot", ls=:dashdot, color=:black, lw=4)
plot!(0:0.1:1, rand(11), label="dash", ls=:dash, color=:black, lw=4)

Is there a way to make sure that the full linestyle is visible in the legend?

A workaround is to plot thick lines, but use a line width of 1 in the legends.

Thanks, that is a good idea!