Double dipping
In Australian political speech "double dipping" is usually when someone whose beliefs don't match yours appears to claim 2 benefits rather than the one to which they may be entitled. A great example arose with maternity leave where the conservative Government offered a scheme but didn't exclude people already getting benefits from their employer. The Labour Party, in Opposition, jumped up and down both on general principles because many of their members didn't have the employer benefits. (There are occasions where all Parties adopt a Nelsonian approach as for example where an MP or Senator - other than those representing the ACT - claims travelling allowance while owning a residence in Canberra. That's not double dipping that is just claiming your due entitlement.) In birding it means to miss out on a bird you are looking for. Sean Dooley gives some extreme examples in Anoraks to Zitting Cisticola. He describes double dipping as missing out on the same