Compatibility issues in two rails engines

We were using the spree engine in the project and everything worked well. when we include another engine called fat_free_crm, there is no issue in the fat-free CRM engine. But the spree helpers are not loading properly. I could not find where the engine overrides another engines helpers. Other than helper loading issue, the spree API's and other functionalities work well. enter image description here

Here is the engine that I have used - https://github.com/krthi/fat_free_crm

below is how the routes file will look like,

Rails.application.routes.draw do
  mount FatFreeCrm::Engine, at: "/crm"
  mount Spree::Core::Engine, at: '/'
end