Can I use Metmin and Azelin nasal spray at the same time?

Yes, you can, especially if the medication is used as directed by your doctor. 

The concomitant use of two intranasal glucocorticoids (mometasone and fluticasone) is not usually recommended due to the risk of increased side effects and lack of additional therapeutic benefit. However, Azelin also contains azelastine, an antihistamine that works synergistically with glucocorticoids. In practice, if the doctor has recommended both preparations, they can be used, but usually at appropriate intervals and under the supervision of a specialist to avoid excessive nasal suppression and other side effects.

If you need more personalized advice, you can use teleconsultations here:

https://www.gdziepolek.pl/telekonsultacja/

Through Gdziepolek, it is possible to book medicines in a selected pharmacy in Polish:

https://www.gdziepolek.pl/produkty/131610/azelin-aerozol/apteki

https://www.gdziepolek.pl/produkty/88706/metmin-aerozol/apteki

I've attached links to helpful entries:

https://www.gdziepolek.pl/kategorie/leki-na-alergie

https://www.gdziepolek.pl/kategorie/leki-na-katar-sienny