Is it an issue to have different addresses (in two different states) on two different W-9 forms that were filled out around the same time, for overlapping jobs?
It's not an issue for the IRS, since the IRS does not get sent copies of the W-9.
The address that you put on the W-9 will probably be the address that they put on the W-2 that you get sent at the beginning of next year, which is sent to the IRS. But this is also not really an issue for the IRS. As long as your taxpayer identification number (social security number) is correct, the IRS will be happy, and the IRS will use whatever address you put on your tax return, not the address on your W-2s.
However, be aware that the address that you put on the W-9 will most likely be the address that your W-2 will be sent to. If you won't be receiving mail in January/February next year at the address you give one of your employers, make sure you give them an updated address.