By Stephanie Stahl

PHILADELPHIA (CBS) — A new chapter in the Veterans Affairs scandal has landed in Philadelphia and will be the subject of a Congressional hearing tonight. This involves the benefits center that processes pensions and compensation.

Federal investigators have found veterans were not getting benefits they deserve in a timely way, and some are being overpaid. The revelations come from whistle-blowers who are working inside the center. One talked exclusively to Stephanie Stahl.

There are claims staff were “cooking the books” to cover up a paperwork backlog and that mail from veterans piled up, left unattended or was shredded. And there’s also evidence taxpayers lost money because payments were duplicated.

WATCH: Local Whistle-blower Sheds New Light On VA Scandal

A whistle-blower claims there’s mismanagement that’s hurt thousands of veterans.

The Veterans Affairs Regional Office in Wissahickon oversees benefits to 825,000 veterans. It’s also a VA Pension Management Center. An investigation from the Office of Inspector General, OIG, that’s being presented to a Congressional Committee tonight has found “a high rate of errors” in processing claims.

“My supervisor at one point told me, ‘Ryan, nobody wanted you because you’re a snitch,’” said Ryan Cease, a whistle-blower who has worked in the regional office for almost five years.

He says he complained to supervisors two years ago about disarray inside the facility and that those concerns were brushed aside.

Last month, he again complained to federal investigators, who responded immediately. Sources confirm Cease is working with investigators.

“When you see something wrong and everybody else knows it’s wrong, but nobody is stepping up because they want to protect their job, to me, that’s messed up,” said Cease.

He claims a quota system to quickly process claims is partially to blame and that staff were “cooking the books,” or manipulating dates to make old claims appear new.

Stahl asked Cease, “What evidence do you have that they were changing dates?”

Cease replied, “Well, we have the memos. OIG actually walked around and grabbed memos from people’s desks.”

The OIG investigation confirmed at least 30 incidences of dates being changed and a rule that allowed the practice has been suspended by the VA.

The snafu may have delayed pensions and other payments to veterans. It’s unclear how many.

“It’s the welfare of the veterans and they need this money ASAP,” said Cease.

He also claims he turned over evidence of duplicate payments, that an unknown number of vets received benefits twice.

“Taxpayers lost a lot of money,” said Cease.

Federal investigators also confirm that duplicate payments were made, but have not yet put a price tag on that.

A statement from the VA says in part that veterans waiting too long for benefits is unacceptable, and that a number of actions have been taken to fix the situation and the investigation is continuing.

Stephanie Stahl