tests/cases/conformance/types/objectTypeLiteral/propertySignatures/numericStringNamedPropertyEquivalence.ts(4,5): error TS2300: Duplicate identifier '"1"'. tests/cases/conformance/types/objectTypeLiteral/propertySignatures/numericStringNamedPropertyEquivalence.ts(6,5): error TS2300: Duplicate identifier '1.0'. tests/cases/conformance/types/objectTypeLiteral/propertySignatures/numericStringNamedPropertyEquivalence.ts(10,5): error TS2300: Duplicate identifier '"1"'. tests/cases/conformance/types/objectTypeLiteral/propertySignatures/numericStringNamedPropertyEquivalence.ts(12,5): error TS2300: Duplicate identifier '1'. tests/cases/conformance/types/objectTypeLiteral/propertySignatures/numericStringNamedPropertyEquivalence.ts(16,5): error TS2300: Duplicate identifier '"1"'. tests/cases/conformance/types/objectTypeLiteral/propertySignatures/numericStringNamedPropertyEquivalence.ts(17,5): error TS2300: Duplicate identifier '1.0'. tests/cases/conformance/types/objectTypeLiteral/propertySignatures/numericStringNamedPropertyEquivalence.ts(21,5): error TS2300: Duplicate identifier '"0"'. tests/cases/conformance/types/objectTypeLiteral/propertySignatures/numericStringNamedPropertyEquivalence.ts(22,5): error TS2300: Duplicate identifier '0'. ==== tests/cases/conformance/types/objectTypeLiteral/propertySignatures/numericStringNamedPropertyEquivalence.ts (8 errors) ==== // Each of these types has an error in it. // String named and numeric named properties conflict if they would be equivalent after ToNumber on the property name. class C { "1": number; ~~~ !!! error TS2300: Duplicate identifier '"1"'. "1.0": number; // not a duplicate 1.0: number; ~~~ !!! error TS2300: Duplicate identifier '1.0'. } interface I { "1": number; ~~~ !!! error TS2300: Duplicate identifier '"1"'. "1.": number; // not a duplicate 1: number; ~ !!! error TS2300: Duplicate identifier '1'. } var a: { "1": number; ~~~ !!! error TS2300: Duplicate identifier '"1"'. 1.0: string; ~~~ !!! error TS2300: Duplicate identifier '1.0'. } var b = { "0": '', ~~~ !!! error TS2300: Duplicate identifier '"0"'. 0: '' ~ !!! error TS2300: Duplicate identifier '0'. }