In detail
Both official sources agree: the High Commission of India’s “VISA DOCUMENTS: CATEGORY-WISE” document and IVAC’s “Kind of Visas & Documents” page each say one photograph.
Two copies are sometimes mentioned. We found that in no official source, so we do not state it as fact.
A correction: this page used to say the sources disagreed (one copy in the High Commission’s document, two in IVAC’s guidance). At the time we could not open IVAC’s page. We have now opened it directly: it also says one, so that disagreement no longer exists.
The photo is uploaded with the online application form. We found no official statement on whether a printed photo is needed at the centre. Keeping one spare in your hand costs nothing. That is our advice, not a written rule.