As long as these are investment properties - I see no issues.
You may have two replacement properties - that is OK.
Or you may use ONE replacement property - and have another purchase unrelated to section 1031.
That is your choice.
There is no time limit to sell the replacement property - you may sell it as soon as you wish - but will recognize deferred gain unless you will be using another section 1031 transaction.
After section 1031 completed - you will report it on your tax return - and will calculate (1) deferred gain and (2) basis of the replacement property.
It is critical that you and your tax representative adjust and track basis correctly to comply with Section 1031 regulations.
Gain is deferred, but not forgiven, in a like-kind exchange. You must calculate and keep track of your basis in the new property you acquired in the exchange.
The basis of property acquired in a Section 1031 exchange is the basis of the property given up with some adjustments. This transfer of basis from the relinquished to the replacement property preserves the deferred gain for later recognition. A collateral affect is that the resulting depreciable basis is generally lower than what would otherwise be available if the replacement property were acquired in a taxable transaction.
When the replacement property is ultimately sold (not as part of another exchange), the original deferred gain, plus any additional gain realized since the purchase of the replacement property, is subject to tax.
Same rules apply to determine long or short term gain.