Include Multiple Legends 

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X styles = Sequence @@ {Axes -> False, Boxed -> False, Mesh -> None, PlotRange -> {-50, 50}, ImageSize -> 400};

Use different legends for different features and place the legends in different locations.

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X Plot3D[Re[Sin[x + I y]], {x, -2 Pi, Pi}, {y, -2 Pi, 2 Pi}, ClippingStyle -> {Orange, Blue}, Evaluate@styles, ColorFunction -> "AvocadoColors", PlotLegends -> {Placed[ BarLegend[Automatic, LabelStyle -> {14, GrayLevel[0.3]}], Right], Placed[SwatchLegend[{Blue, Orange}, {"> 50", "< -50"}, LegendMarkerSize -> Large, LegendMarkers -> Automatic, LabelStyle -> {Bold, 18, GrayLevel[0.3]}], Top]}]

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