I was going to say اسامي is not a Standard Arabic word cause I dont recall seeing it within a standard text then I looked it up = Its Standard according to some textbooks but not commonly used.اسامي used a lot in dialects (mainly egyptian) and اسماء as well.

مرحبا. كلا الكلمتين جمع لكلمة "اسم". أي أن كلاهما صحيح