Cases are transferred between offices to balance out the work load. Though unusual to be bounced around so often, perhaps they sent to wrong office initially. There is a lot of immigration activity so files get moved around in periods of change. You are lucky they are notifying you. Often USCIS moves files around and does not tell the attorney.
USCIS can run their internal operations the way they find fit. Absent arbitrary and capricious finding by a federal judge, there is no way for any of us to control this process.
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All filings are done at one processing office and then it may be moved to a more local office for interview/ investigation/ adjudication. Further movement may be to balance case load at USCIS, company's physical address may have changed, or to correct a previous error. It is be difficult to say. It is unusual for I-140 to be pending for over 9 months without an RFE. Your attorney is doing his part to follow up and update the company.
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