Identify does not always update user values

## Expected Behavior
When I write this:

```
let identify = Identify()
identify.set(property: "someId", value: someValue)
identify.set(property: "anotherId", value: anotherValue)
amplitude.identify(identify: identify)
```

**and** if there was a value for "anotherId" before, then both values should be set to someValue and anotherValue respectively.

## Current Behavior
Currently the second value, here: "anotherValue" is not updated and basically discarded.

## Possible Solution

## Steps to Reproduce
See code above

## Environment
- SDK Version: 353b334924d05c67a85d403584a065999a778c2b
- Device: iPhone 12
- OS Version: iOS 17.1

## Note
This works correctly if `anotherValue` was not set before:
```
let identify = Identify()
identify.set(property: "someId", value: someValue)
identify.set(property: "anotherId", value: anotherValue)
amplitude.identify(identify: identify)
```