The dr hav 2 inhalers for my almost pnumonia. One is dulera (formoterol and mometasone) n my just in case one. How would I know if I need rescue inhaler?

Respiratory symptoms. The rescue inhaler is most likely albuterol which is a quick acting inhaler to open bronchial airways. The symptoms of bronchospasm include shortness of breath, wheezing, chest tightness and a persistent dry or slightly wet cough. If your symptoms are well controlled the rescue medication is usually not needed.
As needed. Almost pneumonia? You probably wont need Dulera (formoterol and mometasone) unless you have underlying asthma, you will need albuteral hfa as needed for short time until pneumonia clears up that too if it's severe pneumonia. You used if you get severe sob or you can hear audible wheezes then up to 4-6 times you can use.