hx-get="" hx-vals="{index: 2}" creates a duplicate entry instead of replacing index

Using htmx 2.0.4.

According to https://htmx.org/attributes/hx-vals/ "Input values with the same name will be overridden by variable declarations."

However when I specify an entry with hx-vals, it duplicates the existing entry, which breaks my backend. This is in an SVG element (rust / maud syntax):
```rust
svg {
g {
line
x1=0 y1=0 x2=100 y2=100
hx-get="" // send to current route
hx-vals=(format!(r#"{{"index":{}}}"#, i + 1)) // update index param
hx-swap="innerHTML"
hx-target=(".target")
hx-push-url="true" { }
}
}
```

- The first request goes to the expected route: `/foo?file=...`
- The second requests adds the index param as expected: `/foo?file=...&index=1`
- The third+ requests fail because they look like this: `/foo?file=...&index=1&index=2`

I tried to use `hx-params="* -index"` which indeed removed index from the request URL. However, this seemed to override `hx-vals` and the expected index was never added to the request URL.

Is this a bug in the hx-vals implementation, or am I misunderstanding the docs? "Input values with the same name will be overridden by variable declarations."