# Double Marker in one PlotLegend

I'm trying to produce a plot to compare two approximations which have in common the same parameter alpha.

I wish to get a plot like showed in the picture:

but I cannot combine the markers and width.

Here is my code:

pTLow[B_, pT_] := B^2/3*4/15*pT^2;
Bw01 = Table[{x, pLow[0.1, x]}, {x, 0.001, 2, 0.05}];

Bw03 = Table[{x, pLow[0.3, x]}, {x, 0.001, 2, 0.05}];

BTw05 = Table[{x, pTLow[0.5, x]}, {x, 0.001, 2,  0.05}];

BTw07 = Table[{x, pTLow[0.7, x]}, {x, 0.001, 2,  0.05}];

ListPlot[{Bw01, Bw03, Bw05, Bw07},PlotStyle -> {Black, Black, Black, Black},PlotMarkers -> {{"\[EmptyCircle]", 13}, {"\[FilledCircle]", 13}, {\[FilledSquare]", 13}, {"\[EmptySquare]", 13}},PlotRange -> Automatic, ImageSize->{600, 600}, AspectRatio -> 1,Frame -> True, FrameStyle -> Directive[Black, Thick, 23],PlotLegends -> {Placed[PointLegend[{"\[Alpha]=1", "\[Alpha]=2"},LegendMarkers -> {{"\[FilledCircle]" "\[EmptyCircle]",20}, {"\[FilledSquare]" "\[EmptySquare]",20}}], {Center,Top}]}]


This is the final result:

As you can notice, there is a problem with the legend width.

• Edit your question to include the code to produce the initial plot. Aug 10 '20 at 23:12

ListPlot[{Bw01, Bw03, BTw05, BTw07}, PlotStyle -> Black,
PlotMarkers -> {{"○", 13}, {"●", 13}, {"■", 13}, {"□", 13}},
PlotRange -> Automatic, ImageSize -> {600, 600}, AspectRatio -> 1,
Frame -> True, FrameStyle -> Directive[Black, Thick, 23],
PlotLegends -> Placed[PointLegend[{"α=1", "α=2"}, LegendMarkerSize -> {50, 30},
LegendMarkers -> {{Row[{"●", "○"}, Spacer[5]], 20},
{Row[{"■", "□"}, Spacer[5]],  20}}], {Center, Top}]]


Alternatively, change the option value for PlotLegends as follows:

PlotLegends ->  Placed[PointLegend[ {"", "α = 1", "", "α = 2"},
LegendMarkers -> Thread[{{"●", "○", "■", "□"}, 20}],
LegendLayout -> (Grid[ArrayReshape[#, {2, 4}]] &)], {Center, Top}]


to get