Those two forms are reporting entirely different things.
That SSA-1099 amount, presumably in Box 3, reports the amount paid to you by the Social Security Administration in 2014. That's "income" to you and some part of that may or may not be included in taxable income, depending on the income you report in other parts of your Form 1040.
That W-2 Box 3 amount, presumably also reported on a 2014 tax form, reports the amount of income paid to you by your then-employer that was subject to the 6.2% Social Security withholding, i.e., the amount of tax that went into your "pot" of funds with the SSA. Box 1 of that W-2 shows the amount of income that you were taxed on for income tax purposes.
So apparently you worked part of the year, earning income that was subject to income taxes (and Social Security taxes) and also retired in that year, receiving some Social Security income. It's coincidental that the two amounts are similar, but they do not represent "double taxation."
Tom Young
