Vetch question

Vetch question

Observation - Vetch question. Description: Can anyone help identify or explain this vetch? It was growing alongside Common Vetch, and while its flowers are the same and also grow singly or in pairs, its leaflets are rounded unlike that of the Common Vetch, as you can see in the photos. I haven't

Can anyone help identify or explain this vetch? It was growing alongside Common Vetch, and while its flowers are the same and also grow singly or in pairs, its leaflets are rounded unlike that of the Common Vetch, as you can see in the photos. I haven't found in my books any other vetches with this combination of flowers and leaf shape, so could this be a variation, a hybrid, or simply another species that I haven't read about?