They should not have issued 1099 forms that each show the full amount. The 1099 should only reflect what each of them received, as the IRS will be looking for each of them to report that full amount on their returns.
If you cannot get the company to issue a corrected form, I would recommend just listing the entire amount on line 16a, but then on line 16b only show half of the taxable amount which is attributable to each of them.
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Thank you kt