Oscar D. or John Gilbert Webb

I was told that this is my great grandfather Oscar D. WEBB b. 1892 IN. But on the matte below the picture has the name "Gilbert" written. Oscar had a brother John Gilbert WEBB who took care of Oscar's wife & children after he ran off to California. So if anyone could clarify this for me I'd appreciate it. Oscar & John G. are sons of Horace F. WEBB b. abt. NOV 1851 IN and Mary A. HECKMAN b. abt. NOV 1858 IN