Some I-140 filed at CSC tranferred to TSC this year. If you think the receipt number is from TSC, it means that your friend case was transferred from CSC to TSC and got approved at TSC. So she filed her I-485 to TSC later.
My question to you is that your friend received the receipt notice of I-485 from TSC on May 23rd. Did she receive finger print notice around that time too?
Thanks.
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As I know, my friend got her I-140 approved on May 10th in california center and she filed her I-485 with Texas service center on May 15th and she got receipt notice on May 23rd, from receipt number I am sure it is from Texas since it starts with "SRC". her PD became current in this May and she did not file her case concurrently. This is all I know. It seems a little different from what you said. Anyway, this is the story I know.