Sir,
Rule 9 of Central Excise rules, 2002 stipulates that every person, who produces, manufactures, carries on trade, holds private store-room or warehouse or otherwise uses excisable goodsor an importer who issues an invoice on which CENVAT Credit can be taken, shall get registered. The rule was amended by Notification No. 8/2014 CE(NT) dated 28.2.2014 w.e.f. 1.4.2014.
Therefore it is clear that only an importer who issues invoices on which CENVAT Credit can be taken has register with the Department as first stage dealer with effect from 1.4.2014. Since you have already registered as first stage dealer you need not register yourself as importer.
Moreover, according to rule 2 (ij) of CENVAT Credit Rules, 2004"first stage dealer" means a dealer, who purchases the goods directly from,-
(i) the manufacturer under the cover of an invoice] issued in terms of the provisions of Central Excise Rules, 2002 or from the depot of the said manufacturer, or from premises of the consignment agent of the said manufacturer or from any other premises from where the goods are sold by or on behalf of the said manufacturer, under cover of an invoice; or
(ii) an importer or from the depot of an importer or from the premises of the consignment agent of the importer, under cover of an invoice.
Therefore in my opinion you need not take a fresh registration.