An improved double Recoverable Block of Function (RBF) system for transgene containment with enhanced reliability is disclosed. The system includes two blocking constructs (BCs) at the opposite sides of a transgene of interest (TGI). The system comprises means for recovery of the function blocked by expression of the blocking genes of the BCs. The invention is also related to a kit comprising a cloning vector having the BCs and TGI or alternatively a place for TGI to be inserted in. Segregating (two-insert) and inducible (one-insert) types of double RBF are disclosed. The two BCs are either similar or different in their DNA and RNA structures. The two BCs may encode same protein but promoters driving the blocking genes are different and/or the coding sequence of the blocking genes is modified by codon preference change. A system comprising two BCs having different blocking genes is also disclosed. The system may consist of one or two Recovering constructs (RC), but also a system recovering without an RC is disclosed. Whether the system includes an RC or not, the recovery is induced by an external intervention that is controlled by human being.