[Bug]: Double instructions

### Mapbox Navigation SDK version

2.0 rc4

### Steps to reproduce

Missed a turn and this started a reroute - so far so good.

but..from that point I started hearing two different instructions.

### Expected behavior

hear only one spoken instruction.

### Actual behavior

Missed a turn and this started a reroute - so far so good.

but..from that point I started hearing two different instructions.

I've attached a video sample (turn audio on), you can see what happens when I take a turn before the guided turn. It starts two different instructions (one says rashi street and the other one says to stay on alterman street). It stayed like that from that turn till the end of the navigation.

### Is this a one-time issue or a repeatable issue?

repeatabl

https://user-images.githubusercontent.com/19625881/136598337-c59da48e-a550-48b4-8232-00c32f6db701.mp4

e

Begin by reproducing the missed-turn reroute on Navigation SDK 2.0 rc4 with turn audio enabled, using the attached video as the reference. No source file or test is named; done means rerouting produces only one spoken instruction through the remainder of navigation.

Written by the indexing model from the issue text.