Azure Pipeline YAML dependsOn already defined

I have a pipeline that will clean, convert a VM to an image, and delete all of the resources. I would like to use that same pipeline to delete VMs without capturing an image. I can make all of the stages conditional, but when I end up with no stages that have no conditions. I keep seeing that the accepted solution to this problem is to make the dependsOn conditional as shown below. the deleteVM parameter is a boolean.

Parameters:
- name: deleteVM
  displayName: "just delete it"
  type: boolean
  default: false
    
- stages:
  - stage: firstStage
    dependsOn: []
    condition: eq('${{ parameters.deleteVM }}', 'false')
    jobs:
    - job: deallocateVM

  - stage: secondStage
    ${{ if eq(parameters.deleteVM, 'false') }}:
      dependsOn: firstStage
    ${{ if eq(parameters.deleteVM, 'true') }}:
      dependsOn: []

The issue is that when I do this, and try to run the pipeline with the second condition being true, it will error when parsing the pipeline: "YAML: ‘dependsOn’ is already defined."

P.S. I’ve looked at the following and they imply that the way I’m doing it is the "right" way:

• Azure pipeline – Stage condition dependson
• Azure Pipeline – Stage with Multiple depends on with if condition

Based on the comments and answers below, I have tried:

Parameters:
- name: deleteVM
  displayName: "just delete it"
  type: boolean
  default: false
    
- stages:
  - stage: firstStage
    dependsOn: []
    condition: eq('${{ parameters.deleteVM }}', 'false')
    jobs:
    - job: deallocateVM

  - stage: secondStage
    ${{ if eq(parameters.deleteVM, 'false') }}:
      dependsOn: firstStage
    ${{ else }}:
      dependsOn: []

Result is "Unrecognized value: ‘else’. Location at position 1 within expression: else."

I have tried to use NOT EQUALS:

Parameters:
- name: deleteVM
  displayName: "just delete it"
  type: boolean
  default: false
    
- stages:
  - stage: firstStage
    dependsOn: []
    condition: eq('${{ parameters.deleteVM }}', 'false')
    jobs:
    - job: deallocateVM

  - stage: secondStage
    ${{ if eq(parameters.deleteVM, 'false') }}:
      dependsOn: firstStage
    ${{ if ne(parameters.deleteVM, 'false') }}:
      dependsOn: []

Result is that no matter if I put true or false, or what I put in the dependsOn in the first position, it skips this stage when deleteVM is true (I think it is ignoring this stage).

I have also tried creating a variable which I had some luck with:

Parameters:
- name: deleteVM
  displayName: "just delete it"
  type: boolean
  default: false

variables:
- ${{ if eq(parameters.deleteVM, 'false') }}:
  - name: dependency
    value: anActualStage
- ${{ if eq(parameters.deleteVM, 'false') }}:
  - name: dependency
    value: '[]'

- stages:
  - stage: firstStage
    dependsOn: []
    condition: eq('${{ parameters.deleteVM }}', 'false')
    jobs:
    - job: deallocateVM

  - stage:
    - stage: secondStage
      dependsOn: ${{ variables.dependency }}

Result is that this will always do the opposite of what I want. no matter if I set the default value to true or false, when I set deleteVM:true, it shows "firstStage" as a dependency, and if I set deleteVM:false, it shows NO DEPENDENCY.

I get that this is interpreted at compile time and this is somewhat the behavior I’m looking for because toggling the deleteVM checkbox switches between having a dependency or not, however, it is always the wrong selection. If I continue with it doing the opposite thing I want, I can see that the secondstage runs without any dependencies (but I have to make the opposite selection of what I want). I would rather not update the verbiage to just say the opposite of what is really going on in the background and I have little confidence in this being consistent across different runs so I don’t trust this enough to merge what I have for people to use.

As someone mentioned in the comment, I am using Azure Stack Hub which has very dated software and hardware limitations…