With a district court’s approval in hand, People’s United of Bridgeport, Conn., is moving forward with the planned re-naming of subsidiary Flagship Bank, despite the protests of Holyoke’s PeoplesBank – as well as a new lawsuit from another opponent, Boston’s Peoples Federal Savings Bank.

The herd of similarly named banks are duking it out in two separate courts, arguing over whether People’s United should be allowed to put its name on the bank’s many subsidiaries, which in the Bay State include Flagship, the Bank of Western Massachusetts, and recently acquired Butler Bank.

Peoplesbank has been battling People’s United since 2008 to prevent that from happening, and had recently filed an injunction to prevent the much larger institution from re-naming its divisions before the case was resolved. The judge denied that request earlier this month, so even though the lawsuit is ongoing, People’s United is proceeding with its plans to re-name Flagship.

Meanwhile, the $488-million Peoples Federal has its own worries relating to the former Butler Bank, which People’s United bought after it failed in April. Butler had locations in Lowell, Andover and Marlborough. Peoples Federal locations are closer to Boston, and though the locations don’t directly overlap, Peoples Federal executives said it was close enough to confuse customers, and was likely to get worse as People’s United expands.

It’s probable that People’s United will make more acquisitions within the Boston area, said Thomas J. Leetch, Peoples Federal CEO, which would put it right in the smaller bank’s territory. Peoples Federal didn’t intend to wait for the $21 billion juggernaut to arrive in Boston before it took legal action, Leetch said.

"They are a threat to Eastern Massachusetts," he said. "We’re firing the first shot."

Despite the setbacks for fellow community bank PeoplesBank in the central part of the state, Leetch is confident that his bank has a strong case to defend its own turf.

"I think we’re on firm footing," he said.