In Dunne's case, his cannibalisation of another party's policy has other drivers. No one can claim a monopoly on ideas - and never more so than when a party's very survival is at stake and the search is on for some means of breaking National's stranglehold on the coming election.
The rash of opinion polls in recent weeks has shown a uniformity that politicians cannot pretend to ignore - National easily clearing the 50 per cent mark, Labour support slipping below 30 per cent and the smaller parties' share of the vote (with the exception of the Greens) seemingly frozen in aspic at basement levels.
The John Key-fuelled National juggernaut continues to sweep all before it. Up against the combination of a popular prime minister, a generally competent Government, voter preference for National as the economic management team for tough times, and the electorate's seeming refusal to connect with Phil Goff, other parties are finding that whatever stratagem they employ to cut back National's lead simply isn't working.
True, people have yet to really focus on their voting options. They may not do so until after the Rugby World Cup, which could stall any momentum a party might manage to generate in the interim.
But no one is getting momentum. Don Brash's attempted resurrection of his hugely successful 2004 crusade against special rights for Maori has looked increasingly desperate as he fails to deliver what he told Act he could deliver as leader - 6 per cent to 7 per cent of the overall party vote.
Act at least now has the crutch of Epsom with which to hobble back into Parliament.
That lifeline is not available to NZ First. It must beat the 5 per cent threshold - and it needs the polls to show it consistently reaching that target to persuade people they won't be casting a wasted vote.
The party is holding its annual convention in Auckland this weekend. Peters will no doubt have some rabbit to pull out of the hat. The question is whether it will be a live one or a stuffed one.
The cynics would be tempted to apply the latter description to Labour's capital gains tax which so far has failed to be the circuit-breaker on which the party was pinning so much hope.
It's too early to write off Labour's overall tax package. Labour has no choice anyway but to stick with it.
Labour has invested too much political capital in a capital gains tax. That capital has been considerably enhanced by the plaudits it's earned for courageously promoting such a tax.
The message underlying the tax - that Labour is willing to take the hard economic decisions that National is shying away from - will take longer to sink in.
Labour's fear now is that fair- weather supporters will jump ship as they realise Labour has little or no chance of winning the election.
The theory goes that they will then look for parties able to constrain a second-term National Government. This is the 2011 version of National's 2002 election apocalypse which saw that party's vote plunge to just above 20 per cent and its seats in Parliament drop from 39 to 27.
While a repeat cannot be completely discounted, the odds are against that happening to Labour. The party has been polling consistently around the 33 per cent mark it secured on election night in 2008. Its tax policy should reinforce that core support.
Dunne's talk of United Future once again being a moderating force on the major governing party and saving it from the "extreme tendencies" of Act is laughable given that United Future is polling below 1 per cent and Dunne will have his work cut out holding his Ohariu seat.
National's refusal to work with Peters means his capacity to restrain National would be limited to voting down legislation from Parliament's cross-benches.
That also assumes National doesn't win an absolute majority. Voters denied Labour that luxury in 2002.
The crucial difference now is that National has actually flagged something of a post-election lurch to the right in the form of state asset sales, more state sector cuts and a strong dose of welfare reform. But this has made no impact on its poll ratings.
Peters' warnings this is a watershed that will see a return to the "failed" market-oriented policies of the 1980s and 90s are simply being ignored by voters.
This election may instead turn out to be a watershed for another reason. With Jim Anderton quitting Parliament and Dunne and Peters in electoral bother, we may be watching the dinosaurs who survived the 1996 switch from first-past-the-post to MMP finally moving on.