Describe the bug

Looking at #19114 the code will The following code will forget conditions when the only difference is in the value tested, example:

const p = new PolicyStatement;
p.addCondition("StringEquals", {'sts:ExternalId': '12345678901'});
p.addCondition("StringEquals", {'sts:ExternalId': '01234567890'});
console.log(p.toStatementJson());

will forget the first condition, generating:

Condition: { StringEquals: { 'sts:ExternalId': '01234567890' } },
Effect: 'Allow'

instead of

Condition: { StringEquals: { 'sts:ExternalId': ['12345678901', '01234567890'] } },
Effect: 'Allow'

Expected Behavior

Not forget conditions

Current Behavior

Forget conditions

Reproduction Steps

import {
    PolicyStatement,
} from "monocdk/aws-iam";
const p = new PolicyStatement;
p.addCondition("StringEquals", {'sts:ExternalId': '12345678901'});
p.addCondition("StringEquals", {'sts:ExternalId': '01234567890'});
console.log(p.toStatementJson());

Possible Solution

No response

Additional Information/Context

No response

CDK CLI Version

1.124

Framework Version

No response

Node.js Version

17.4

OS

macos

Language

Typescript

Language Version

No response

Other information

No response