Can the shipper also be consignee ?

Absolutely. To understand this first we need to understand who is a shipper and who is a consignee.

A shipper is a party who arrnages for the transportation or a carrier (for example a ship) to transport the goods. If seller of the goods arranges for the transport, seller becomes the shipper of the goods. 

If the buyer of the goods arranges for the transport, buyer becomes the shipper of the good.

Shipper then hires a ship (or other transport) and enters into a contract with the carrier. This contract is "Contract of carriage".

Consignee is the party to whom the goods need to be delivered. For a carrier (or ship) it is important to know to whom the goods are to be delivered.

In the cases where buyer of the good is the shipper, the buyer may want the goods to be delivered directly to them. In this case the shipper will also be the consignee.