Organisations can call themselves what they like. Barclays Bank may have been started by Mr Barclay, but it could have called itself Barclayz Bank if it had chosen, so we should be grateful for Barclays Bank.
Words (invariably names) which already contain an apostrophe cannot be made further possessive. So McDonald's has McDonald's employment practices, never McDonald's's employment practices. If it troubles you (because McDonald's staff should be the staff of McDonald) try to convince yourself that we often don't use a possessive anyway: PC World staff will evict you is just as acceptable as PC World's staff will evict you.