Fix currency duplication bug (#32524)

Content.Server/Store/Components/CurrencyComponent.cs

@@ -8,6 +8,11 @@ namespace Content.Server.Store.Components;
 /// Identifies a component that can be inserted into a store
 /// to increase its balance.
 /// </summary>
+/// <remarks>
+/// Note that if this entity is a stack of items, then this is meant to represent the value per stack item, not
+/// the whole stack. This also means that in general, the actual value should not be modified from the initial
+/// prototype value because otherwise stack merging/splitting may modify the total value.
+/// </remarks>
 [RegisterComponent]
 public sealed partial class CurrencyComponent : Component
 {
@@ -16,6 +21,12 @@ public sealed partial class CurrencyComponent : Component
     /// The string is the currency type that will be added.
     /// The FixedPoint2 is the value of each individual currency entity.
     /// </summary>
+    /// <remarks>
+    /// Note that if this entity is a stack of items, then this is meant to represent the value per stack item, not
+    /// the whole stack. This also means that in general, the actual value should not be modified from the initial
+    /// prototype value
+    /// because otherwise stack merging/splitting may modify the total value.
+    /// </remarks>
     [ViewVariables(VVAccess.ReadWrite)]
     [DataField("price", customTypeSerializer: typeof(PrototypeIdDictionarySerializer<FixedPoint2, CurrencyPrototype>))]
     public Dictionary<string, FixedPoint2> Price = new();