You'll need to contact the previous employer for an explanation. It's possible that the distribution from the 401(k) at the previous employer has nothing to do with your reporting to them of excess elective deferrals to the two plans combined but is instead a distribution that was required because of the plan at the previous employer failing non-discrimination testing.
It's still possible, though, that the distribution made from the previous employer's plan was the result of you informing them of you having made an excess elective deferral. Because of investment losses, the amount distributed as a corrective distribution of your excess elective deferral was required to be adjusted (downward) proportionate to the overall loss in the account.
I would expect both plans to report these distributions with a code that indicates that they are ineligible for rollover, but it seems like one of these (or at least a portion of one of these) could be treated as a regular distribution which is eligible for rollover since receiving both has brought you below the elective-deferral limit. Taking this position and within 60 days rolling over the portion that was not required to be distributed could be problematic, though, because it would require that the IRS accept your explanation that this portion was actually eligible for rollover, despite the plan reporting otherwise. Whether the IRS would accept this position is unknown.
