ruby on rails merge two yaml files in a unique yml file

i have 2 yml files:

#1.yml
devise:
  omniauth:
    app_id: "some"
    app_secret: "aa"
    app_name: "aaa"

#2.yml
secret_token: "qqqq"
devise:
  omniauth:
    app_foobar: "some"

i want to obtain a unique yml file like this:

#merged.yml
devise:
  omniauth:
    app_id: 
    app_secret:
    app_name: 
    app_foobar:
secret_token: 

i want to merge the files without the value, only with the key. Is possible with ruby and rails?